Check with somebody in admission on the x-c time question. You'll probably be going into step II which includes a lot of solo x-c, so building time earlier might be redundant.
I'd definitely recommend staying current in a Piper Cherokee. Be sure that you can perform the maneuvers to private PTS standards.
If you can get a copy of FSA's Cadet procedures manual (maybe when you come to tour the campus), you might want to go ahead and start using it for familiarity and to study the memory items.