Stick to the 50 profile, they're better than a 45 profile unless you're going to get bigger wheels. I have 45 profiles but they're 16's, so I was trying to keep to the same rolling diameter as the standard wheels.
As for lowering, forget the gmax kit - it looks good but your can't won't handle as you want it to.. unless of course you like to dip, dive and bump steer around corners! The eibachs are a very good choice and will work with your standard shocks fine - if however you want to uprate shocks too then get some from Bilstein. Polybushes all around will firm up the ride without making it too harsh on bumps too.
Mark