Hmmmm, I forgot to give some advice with my anecdotes.
Cats and kittens LOVE boxes. Keep a couple of boxes around the house at all times, just for the kitties to sit in. For some reason, sitting in a box is very satisfying for cats, so let them sit in them. Cats also like paper bags and laundry baskets and all sorts of containers…which leads me to my next point.
Get a couple of adult sized cat carriers now, and leave the doors open so the kittens can come and go in the carriers. You WILL need to take the cats to the vet every now and then, and if they already think of the carriers as “neat places to hang out” instead of “PRISON!!!” then everyone will be much happier.
Start brushing both kittens now. Let them get used to it. Most cats enjoy being brushed if they’ve experienced it as kittens and they’re used to it. It will help reduce hairballs, and it will reduce the amount of cat hair on your furniture. Some cats even like to be vacuumed, which is the ideal solution.
Start clipping their claws now. It’s actually pretty easy to do, though I find that having two people do it helps a lot. One person holds the cat, while the other person does the actual clipping. Be very, very careful not to clip into the blood vessel in the claw. I just clip off the very points of the claws, which causes my female cat to get aggravated at me, as she had JUST gotten those claws sharpened to a nice point…
Personally, I don’t think that cats need to be bathed by humans, unless the cat in question has gotten itself really filthy, or is covered with a toxic substance (soap, or gasoline, or some other chemical which they shouldn’t ingest). Some people feel that cats need to be bathed regularly, but I have never bathed my cats except for those unusual circumstances that I’ve noted. Since you are keeping your babies inside, you probably won’t need to bathe them. Some cats like water, and like being bathed. Most object to it quite strenuously.
Anything not nailed down is a cat toy. Anything that IS nailed down is a scratching post. Oh, get them a scratching post NOW and show it to them. Put it wherever you want to keep it, as cats like to have their food, water, litter box, and scratching post in the same place all the time. Take the kittens, one at a time, and hold their front legs. Move their front paws against the scratching post while making sounds of approval. This will encourage them to use the scratching post. If you catch them scratching anything else, grab them and take them to the post, and again move their paws against the post while giving them praise.