You should be good to go....
Hit up Op-For
if you haven't already. Those are the places to get in on the local games and they're the major clubs in Vancouver/Lower Mainland.
There should be someone there at the field to verify you.... I believe that there may be one person who works at Daves Surplus who does AV too.... I'm not 100% sure but you could probably call them up and ask (I've heard the name "Colin" thrown around a few times but I'm not 100% sure that's the guys name or even if he does AV).
For me personally my gundoc told me he believes my spring may be an M110 so I'm getting like 360-380 in my gun and I find that .25's are my favourite to run with. I used some .28's today and there is a difference but I'd say unless you're shooting above 375 then don't bother with .28's. This is my personal opinion but do your thing and find whats right for you.
Range actually goes slightly up with heavier BB's (to a certain point, with a certain speed) but you run the risk of people doing the "matrix thing" and dodging your BB's if they're going too slow.
Also talk to Optix about getting a "sampler pack" of the BB's he's selling. Just pick up a bag of each .20's, .25's and .28's and test them all out and see what you like.