Do I need to have an appointment just to get a trouble shoot checking for my phone?

You are much better off making an appointment - Genius Bar Reservation and Apple Support Options - Apple especially as they are likely to be overloaded because a new release has just come out. But you can walk in and if they have any no-shows you may be able to see a technician. But be prepared to wait for multiple hours.

That depends on each individual store and how long their waitlist is; depending on how busy they are they may not be able to take walk-ins. It's highly advised you schedule an appointment.