Would they do repairs on a old Bass?(I think it’s a Bass, it’s a hand me down so I don’t know much about it) If they do repairs around how much would it cost? If repairs are possible would I have to make an appointment or do they do walk-ins?

Am not too sure if they repair it themselves (staff) because it does requires a specialist depending on what you're trying to get done. But I'm sure they can direct you to a 3rd party who can help if they cannot. Bass typically has 4 (big) strings. Regular acoustic can have up to 6 or 12. Anyone, please correct me if I'm wrong.

Yes they can i would call before going though because of Covid idk if they are doing walk ins right now