Smokey loves to go play outside, then come back inside soaking wet and jump up in my lap or rub against my bare legs. So I think I dislike being wet more than he does. 
He loves to jump up on the sink when I’m washing dishes and sometimes he helps by licking the dirty ones clean. Luckily, he hasn’t yet tried jumping into the sink when it’s full of water.
Or wrap the pot in a plastic bag and tie the top shut so the cat can’t get in. Adult cats may also mistake potted plants for litterboxes; my sister and I have both lost large potted plants this way.
TV personality and cat advocate Jackson Galaxy often recommends making high places for cats to look down on their surroundings – cat trees, shelves, windowsill rests, and so forth. This improves their environment and often seems to calm down troubled cats. Kittens may need ramps until they are bigger.
Forget ramps–just hang down a piece of thick cloth for them to climb.
We have three kitties, one old Maine Coon and a pair of littermates we took in as kittens. The little ones had a habit of climbing on things where they shouldn’t, like the stove or the toaster oven. Fortunately neither were ever on when they were and their knocking over a bunch of pots & pans put a stop to that. All that racket scared the hell out of 'em!
Don’t cheap out on trees! You want one with a solid wood core, not those things with the cardboard & plastic pillars that require assembly. Our trio went through at least two of those cheap things. Thankfully they were never injured when a support collapsed under them due to a plastic end cap failing.
I have to hang my winter coat in the closet; draping it over a chair isn’t sufficient because - you guessed it - one of my cats has tried to climb it.
As far as knocking things over, I worked out a rough test for what to be concerned about. Approach the object of concern, drape your arm over/around it at about whatever level a cat is likely to come into contact with it, and then step backwards. Don’t grab with your arm, just relax it and drag it away from/over the object. If the object moves or falls over, the kittens will murder it within 36 hours in the course of normal prowling. And don’t think for one minute that a shelf might be too high for the kitties, and therefore safe. Cats are driven to occupy for as long as possible the highest point in a room (that’s how you can identify today’s top-cat).
Which brings me to my second point. Cats growl, hiss, and swat each other as part of their normal discourse. If there is an altercation and neither is trying to escape after 10 seconds, you’re just witnessing a negotiation of some kind. It can be alarming, but it’s best if you let them sort it out in terms cats understand and don’t go imposing monkey rules on them. Cats are great souls, but they really aren’t all that interested in what the monkey wants, so much as what the monkey is doing (until they’re around 5 or so years old–then they’ll show some empathy when it suits them). That’s why it’s hard to discipline a cat.
No concern about that here; the littermates are too afraid of our winter coats! And the Maine Coon isn’t much of a climber.
I’ve scoped out articles for the top rated cat trees for Main Coons, figuring what’s sturdy enough for the biggest cat will be more than adequate for the other two. Besides, you never know how big the rescue kitten will be - Shamus’s best friend Sassy was a short-hair tabbyvand she was nearly as big, bone structure-wise, and often heavier than him (at a mere 14lbs he was rather delicate for a Maine Coon, probably the runt of the litter). The cat tree I have in mind looks like it’s a lot of fun with lots of places to perch
FEANDREA 67 inches Multi-Level Cat Tree for Large Cats, with Cozy Perches, Stable UPCT18G https://www.amazon.com/dp/B071CFXMZG/ref=cm_sw_r_cp_apa_i_VAGqEbMSXCPRZ
That’s the sort of thing I was referring to; those plastic end caps will fail eventually due to the kitties jumping on and off the top and side platforms.
This one is nearly identical to what we have now, the only difference is the top platform. We also have this without its top platform next to the big one. The smaller one is cardboard & plastic but pretty sturdy anyway with the opposite corners supported.
Especially a hazard if you have a gas stove.
Never leave an open flame, of any sort, unattended around kittens. If you can avoid even having an open flame at all, that’s better yet.
Depending on what it’s made out of, they may try to eat it.
Very much this; and even if one is trying to escape, it’s probably OK. If it really looks out of hand, a human can pin down the aggressor briefly to prove they’re not the largest one in the house, and to let the losing kit get a breather; but don’t worry about it further than that.
If one kitten’s chronically hiding from the others in terror all day long, and not just for the first day or so, then there may actually be a problem. It can happen; though it’s unlikely, and very unlikely with young kittens.
But if one kitten’s even chronically pinning another down in wresting matches with resulting screeches and hisses and pinned-down kitten fleeing and even a bit of fur and/or blood loose sometimes, but twenty minutes later the kits concerned are curled up together snoozing – that’s just cats being cats. I had a pair of littermates (still have one) who did that every morning for probably ten years. And loved each other to the end of the life of the first one to go, sixteen years later.
You spend the lifetime of an adult cat saying “Aw - I wish you were still a kitten, you were soooo cute”.
You spend the time with a kitten saying “Hurry up and grow up, you total pest!”
My litter-tray training technique: Place kitten in litter-tray. Grab front paws of kitten and show them they can dig in the litter. Training complete.
Be aware that kittens have three operating modes:
Fully powered down: so sound asleep you’ll be checking that they are still breathing. This happens anywhere, not just something designed to be a cat bed.
Stand by mode: similar to above, but with added purrs. Frequently on lap.
Powered on: sideways bounce bounce bounce, attacking things that aren’t there, shinning up curtains, charging from one room to the other, generally being a little bundle of madness. The simple act of “walking from one room to the other” doesn’t really seem to feature.
Toys: It’s true that you don’t need to spend much, if anything. Shiny bits of paper, bottle tops, plastic straps cut from a parcel just for starters. Mine love the foil lid from a San Pellegrino soda can scrunched up into a little ball and thrown across the room.
However, for my latest little one I got a pack like this from Amazon https://www.amazon.com/Youngever-Kitten-Assortments-Tunnel-Feather/dp/B077B9PHKD which is a very worthwhile investment. He loves the tunnel and sleeps in it.
Different kittens will also have different… call it avenues of mischief. One might have a tendency to climb on high shelves and knock over your porcelain figurines, while another is safe around shelves but you can’t leave your breakfast unattended.
On a more positive note, watching kittens chase each other around the house is some of the most solid entertainment you’ll see all day.
I brought two feral kittens in from the cold just a couple of months ago. Don’t really have any advice to add, but I do have a mess of photos of them being adorable:
In most of these they’re still wearing their post-spaying kitten onesies in lieu of the “cone of shame.”
I love that they’re sisters and they’re already bonded. Our two older cats barely tolerate each other. They’ll sit in the same room together, but they’ll always be facing opposite directions like they’re pretending the other one isn’t there.
Wait 'til they’re older. 
Our brother & sister pair were bonded as kittens but now they sometimes can barely stand each other and have wrestling matches at feeding time. Once in a while they will share the big tree but usually one will chase the other off the top.
We scooped Bullet and Guillermo The Relentless out of a junk yard this past July 4. About 6 weeks old. They are sweet and cuddly like you’d expect, but there’s a level of cleverness to them that, whether true or not, is readily attributed to coming from a couple generations of wild living. I’ve gone through some cats in 50 years, until now I never had any that worked out how to open the (correct) cupboard, pull down the treat container, unscrew the lid, and gorge on treats. These little monsters have also sussed doorknobs and coordinate attacks with diversion on the dogs: one will sit in front of a dog and coerce it to touch noses…while the other sets up for a pounce from behind on the unsuspecting pooch. Yeah, 7 month old kittens using 100# dogs as toys. I might be in over my head.
Could happen.
But I’ve had siblings – and for that matter sometimes cats who met as adults – who stayed bonded all their lives.
Look out for strings, yarns, twine, tasty cloth wrapped wires, stuff like that. My bestie’s kitten spent last weekend in surgery for having swallowed some kind of string with a wire core. It did a lot of damage, he’s still in recovery.
My kittens used to love origami balls. They are put together out of 12 small folded pieces of paper, and they rattle madly when they roll because of the 12 points, and when you whack them enough, they fall apart into separate paper things. Fun! 
This is it: Modular 12 Sonobe Unit ball.
https://www.youtube.com/watch?v=QwB8OdV2FDM
