go with another Bell Helmet man. we have just come out with some new SA2010 helmets and you should start to see them anywhere Bell helmets are sold. (i work for Bell) i could probably get you a discount on a helmet but with shipping it might equal out to be the same if you just ordered one. find one you like and i'll see what i can do.
rota slips in the 15" will fit. you can find them at 18racing.com
as for tires, in the 16 series i would also recommend the Kumho Ecsta XS tires in the 215/45/16. i think those will out grip the Gsport & DZ101s after being warmed up a bit.
the sport Z1s will out grip the kumhos but the sizes aren't the best. (225/50/16; 205/50/16; 205/55/16)
i think the 215/45/16 will be your best bet with the gearing on these things.