#1
im getting these 3 pickups

Neck: Seymour Duncan SH-2n Jazz
Middle: Boutique 5.55k strat single coil from GFS
Bridge: Seymour Duncan SH-4 JB model

I have a 1 vol, 2 tone setup, and my volume is going to by a push/pull for a coil tap,
im wondering what value pots i should use? Usually 500k's are used with humbuckers but ive heard some sound better with 250k's...?
#2
500's would brighten the sound a lot when the coils are tapped, but would be best for the single coils. It all depends on what sound you want.
#3
I would use 250k with those pickups. The JB has pronounced highs that the 250 will help roll off. 500k pots bring out the high end and might be too much in that configuration.
It's a fine line between clever and stupid.