I'm Aura and I'll be playing in Group A. I'm in my 40's and have been gaming for quite a while, sometimes as the GM. As for the questions four:
Your experience with the rules
I wasn't in on Pathfinder since the start, but have now been playing for a few years or so. Although I play other things as well, PF is my default goto game.
Your experience with PbP
I have been a PbP player and GM for a couple years now, over on ENWorld.
Expectations for playing and what you want out of the experience
Basically, it comes down to the desire to emote. Encounters are just situations that give us the opportunity to display how our characters behave, IMO. I actually am not big on the concept of challenge, although some play for that. As a GM, I know encounters are, for the most part, built to be winnable (virtually by default), so I look at it as a participatory movie, where the audience forms the scene. (This said, I keep building sub-par characters, but, ya.)
Anticipated frequency of participation
I generally check PbP games every other day, and anticipate I will continue to do so.