I don’t know all of the IO options - it depends on the platform you’re playing on. For me on PC you click the joker and then click “Buy”. On iOS it’s dragging it into the “Buy” area that appears when you tap the joker.
“Discovered” just means that you’ve used the Joker in a game before. Some jokers are “locked” until you compete some in-game criteria. If you go to the “collection” on the main menu it will show you the locked jockers, and sometimes what you have to do to unlock them.
This is not true. Any unspent money in a shop stays in your bank, and potentially earns interest. You do not have to spend all of your money - and in fact you probably shouldn’t!
Probably not.
Here’s a quick idea of the first three rounds (first Ante).
Round one: You won’t have any jokers, and you need 300 chips. This can be done with a high flush (more than 30 chips worth of cards) or a high straight (more than 35 chips worth of cards). A Queen-high straight works, or normally a flush with a few face cards. You should be trying to win with only one hand, by using your discards aggressively, typically to find a flush. If you don’t make a flush you will need to play some hands to try to find the flush - so if you end up with only 4 cards of a suit play the other cards as a High Card or Pair to hope you draw the flush. Then play the flush to win.
First shop: If either of the Jokers offered to you are a scoring joker, you should probably buy it. By “scoring joker” I mean one that directly gives you more points per hand. Something like the one that gives +5 per face card played, or +mult to a specific hand type. This will make the next few shops easier. If there are no scoring jokers, but there is a buffoon pack (which has jokers in it), open that and grab the scoring joker there. If you don’t have that option, just go next and save your money.
Round two: You will need two or more hands, unless you got a scoring joker. Again, try to win with in as few hands as possible (each unused hands earns $1 at the end of the round).
Second shop: If you didn’t get a scoring joker, you will need one now. Grab whatever is available, and focus your play around that joker for the next few rounds. Any +mult is great to get through the next few rounds. If you already have a scoring joker, look for ones that add money (Golden Joker is great, as is ToDo List or ones that give money for discarding certain cards). Don’t buy more than the one scoring and one “value generating” joker until you get $25.
Round three: This will have some boss ability that will make it harder. Hopefully you have a scoring joker, in which case you should be fine with two good hands. Make sure to play the hands your Jokers help with.
Thirds shop: Now you should have some money. You can grab a second scoring joker if you want, but don’t open the bonus packs until you have $25 to earn max interest.
Some other general advice:
Another approach if you are given planet cards is to use them to get through Round 1. If you upgrade Straights, for example, you can get through at least Round 3 or 4 with just one straight.
For low stakes you should try to have one scoring joker per Ante you are in minus 1. So by Ante 3 you will need two scoring jokers. By Ante 8 you will likely need all 5 to be scoring, unless you have some of the really strong ones.
Try to spread out what the jokers do. Scaling jokers are better than static ones (i.e. ones where the amount of scoring goes up over time). The ideal setup is to have: one scaling chips joker (Castle, Square, Wee), one scaling mult (Green, Red Card, Supernova), one scaling xMult (this are much rarer, but Constellation is a good example). If you get even two of those three with some static joker for the other you will almost certainly win.
Don’t buy more than you need! Keep track of what your hands are scoring and you can look at “Run Info” to see the next blinds levels. If you are scoring 2000 chips with a pair, and the next boss is only 3000, you don’t need to spend all of your money on scoring - either save it or use it to improve your deck with tarot cards.
There is much, much more - just keep playing!