Follow up question - would you learn dances for every specific song or learn general genre dances? Also, was there any space to 'break it down' and improv at a courtly gathering?

Follow up question: would I pregame? Or would that be seen badly?

You do generally understand what dances will be played, and from there it's about matching your knowledge of dance steps, ingrained as a part of social existence from a very early age, to the dances that are given. You aren't likely to have foreknowledge of the specific minuet or sarabande that's going to be played that evening, but it doesn't matter, because the dance steps remain the same no matter what specific realization you are listening to. On this point, /u/kittydentures answers just about all the questions that you need.

So for the rest of this post, let me elaborate on just how crucial it was to demonstrate your inward nobility through outward grace. Manners at court was an essential part of being a galant gentleman. This is expressed pretty clearly in the following letter from the Earl of Chesterfield to his nephew.

I was very glad to hear, from one whom I think so good a judge, that you wanted [ie, lacked] nothing but des manieres, which I am convinced you will now soon acquire, in the company which henceforward you are likely to keep. But I must add, too, that if you should not acquire them, all the rest will be of little use to you. By manieres, I do not mean bare common civility; everybody must have that who would not be kicked out of company; but I mean engaging, insinuating, shining manners; distinguished politeness, an almost irresistable address; a superior gracefulness in all you say and do. It is this alone that can give all your other talents their full lustre and value; and, consequently, it is this which should now be the principal object of your attention. Observe minutely, wherever you go, the allowed and established models of good-breeding, and form yourself upon them.

Observe minutely: judgment and taste were integral to success in courtly society. Knowing the dance steps themselves was the bare minimum of what one had to do. One had to master the dance steps to such a degree that one could perform them with supreme grace. One wouldn't dream of stepping into Versailles of all places unless one had an absolute mastry of dance and dancing. As with everything with galant society, mastry involved far more than just producing correct steps to dances, but also in carrying yourself well, leading your dance partner well, etc. Every physical gesture you made mattered to your success at court, so you couldn't waste mental effort on banal things like the basic dance steps. Those had to be ingrained as completely natural and intuitive. But hopefully, you would have had access to a (French) dancing master from an early age who would ensure that this was not a problem.