do I need to make an appointment to purchase and install tires or is it first come first serve?

Appt to buy, no. Appt to install nice if you want to get in and out faster

I would make an appointment, they are usually booked so your appointment may be a few days later. Also make sure you hand the wheel nut key if your car requires one or else they will go three you car looking for it..

First come first served. You are able to make an appointment for the installation. I recommend calling in and seeing if they have your tire size in stock before making any plans.