"Any GPS recommendations?"
If you get one with pre-loaded maps, check out the scale --- a friend doing the CDT this year got the Garmin Colorado and it has preloaded maps, but at 1:100,000 scale. I prefer at least 1:50,000, and more typically 1:25,000. Typically you can buy such as an additional cost. For most of the PCT a GPS is very infrequently comforting but not necessary, but for a SOBO start, you might want one in the northern area. I just used the GPS in my smartphone, got Topo's software for using their (NG Topo) map data that way, worked well enough.
"Also, for those of you with thru hinking experience, how many pounds of food / calories were you carrying per day?
Did this differ depending on the conditions and amount of time you'de been hiking?"
Last question first, yes it definitely changes. For some people it takes a couple of weeks, for me it took a month before I had thru-hiker hunger, YMMV based on metabolism, starting body fat, etc. Normal for me in "normal" conditions is between 1 to 1.5 pounds of food a day, but I regularly at least 2 pounds or more per day when fully up to speed, and like many I think, was still perhaps losing weight between trail towns and somewhat compensating by eating like a pig in trail towns.
I don't recollect what this works out in terms of calories per day, but this was with a general attempt at a high calorie diet, things like adding olive oil to any dinner meal.