AN EXPERT!!!! oh wow, dont be so humble. I'm sure in high school you have ALL the answers. Dont even worry about getting a history degree in college, i'm sure as an expert you can skip that.
Go to college and get a degree in some sort of history, then see what you can do.
The compression wouldnt tell you if you would need a water pump. That'd be more to check for a blown head gasket. Where is it leaking from? That'd be what I'd look for.
Honda definitely.
Suzuki has had frame recalls on their late model GSXRs and I've not really heard great things about their 750's and 1000s.
Kawasaki I've got no prior experience with.