It depends on the airline. The international gates BA uses are in a terminal shared with Southwest and US Airlines. There may be a couple of other partners there. AA, UA, AS etc. are in other terminals and you'll have to take a landside bus. I wouldn't worry too much about security - it's usually quick in PHX and there's a premium line.

That terminal is big, though it's possible to walk right round the airside. There are bars and restaurants dotted round the piers though as others have said, none of them are anything to write home about.