Undies with a catheter is your choice. As I recall I did. But comfort with that hose is the decider.
Buying supplies now is up to you. I'd only suggest you get like one pack of each of whatever you'd like to try. That way you can change your mind without a bunch of product you may not like.
It could take a little time to find out what you like and how your body reacts to all the surgery, etc. Take it easy and proceed with what works for you.
All the best.
bob