I got the specs for the XJ750X from here, it is the only site I could find with the XJ750X specs, all the other sites has just the XJ700
http://www.skylinc.net/~hap/maxim-x/specifications.html
I don't remember where I found the GSX stats, it was a link from another forum somewhere.
the XJ750X has more torque than the GSX, and torque is what sets things in motion, hp is more related more to top speed. You need both to go fast but torque is what really drives lower end acceleration. Also I don't know the gearing but the Maxim hits it's powerband at a lower rpm than the GSX. I'm not arguing that it is faster I'm just saying that it seems like it is a pretty fast bike and that there are tons of factors that lead to acceleration, many more than just weight and hp.
And for the questions...
I haven't taken MSF, but, I am signed up for MSF in May
I haven't bought all my gear, I already have some good quality leather jackets and I bought a snell rated helmet (it's pretty sweet looking )

, so I just need some chaps/pants and some good quality boots and gloves.
In minnesota here it was -25 Fahrenheit yesterday, it should warm up soon though (late march). I will be riding a smaller bike for awhile before I move up to the XJ750X, it's a 250cc Honda Helix, no manual gear changing but hey it's got two wheels and is the best I could find.
The reason I chose these two is the price I found them
Helix: Free, just needs a tuneup.
The XJ750X has only 5,000 original miles on it and is so clean it's not even funny, I got it for $700, it has new fork seals, a tuneup, some new electrical work and new tires. I thought it was a good deal.