Good luck, Sebastian!
I've never busked so I have little personal experience to share. I have performed on stage in public spaces (rock/pop bands) and casually played in public spaces (including solo classical and finger-picking). About a hundred years ago, I briefly followed a busker around for a college research paper.
Despite the inadequate qualifications, allow me to suggest that, for the most part, the answers to your questions are so specific to particular locations, times and transient crowd make-up that you'll likely get better answers from an hour of first-hand observation than anyone here can give you.
Beyond that, I won't presume to lecture you on safety, but that's first. Secondly, if you don't know the area well, scout. For good reasons, buskers prefer places like plazas and transit stations at busy times. Spend time in promising places and watch what happens. Mingle with the crowd, find out what the audience likes from their point of view.
Obviously, talk to the buskers (if any).
Something one may not think of: Of course, you'll have to be on good terms with the local police, but they are also potentially your best informants if you can get them talking. Just like anyone else, they have relationships to and opinions about music, but they are also trained observers, and they've been at the scene day in and day out. They can tell you what's popular, what spots sound best, which spots attract thieves or panhandlers, or get overrun by rushing commuters.
As for repertoire, I'm sure you realize that your answers can only come from doing and experimenting. Variety, material you know so well that you can pay some attention to the crowd. Don't make too many assumptions. I've seen buskers do well with just standard classical repertoire, even studies. Office lunchers and tourists don't necessarily want the same thing. Some crowds are mostly the same day to day, while others change daily, hourly, etc.
I'm just belaboring the obvious, now, so again good luck, and enjoy yourself! And let us know how it goes!