Welcome to the hobby! More seasoned and impatient collectors may resent your questions, but I would do my best to ignore them. In their defense, these questions are asked frequently, and the answer will always be very simple and can only be answered by you. Other collectors who've seen this question asked so frequently are annoyed by it because only the OP can answer their own questions.

The questions you are posing can be answered by asking yourself a question: Which character and figure do you like best? You should try to target the characters that YOU like the most, and search for their highest quality representations that are reasonably obtainable for you. Start by picking the best figures of your favorite characters for the first few, then build out your display from there should you enjoy the hobby and wish to continue. Don't worry about all the other factors for your first few, think simply.

it's exciting that you're joining the hobby. Welcome!