Hi KirzeTheCat,
Welcome to the forum.
Usually, if someone asks “how can I make a game like…” the chances to get a reply is very low. This is either because people don’t know the game you are mentioning or they assume that you ask them to walk you through making an entire game.
So when I read the title of your post I thought it is very similar, but you have actually specific questions, which is much better. I would suggest that you ask one question per topic and choose a title that is somehow reflecting what your request is all about.
For your first question, you can find a solution in this thread:
which could look like this:
This spawns objects randomly on one tile (sprite-object). I guess that’s not what you actually want but it may be a start.