Sounds to me like your bike is on the verge of stalling because youre not matching your engine speed with your road speed. If you’re in a higher gear and slow down or drop in rpms, you need to downshift to keep your engine from stalling out. I usually shift at around 6k and will keep anywhere from 4-6k when commuting. It also kind of depends on what bike you have because sometimes 4k is too buzzy for me. At any rate, you dont want your rpms to be too low or too high. Make sure that you also engage the clutch when coming to a stop or doing any significant braking, otherwise the bike will stall, which will lead to a dropped bike if you arent careful. You will get a good grasp of all this when you take your class. Personally, I wouldnt do too much riding until you actually take the class. You dont want to learn any bad riding habits or mess up your new baby by commiting a simple error. I would use the 2 weeks to complete all of the maintainence that was discussed above, that way as soon as you get done with the class, the bike will be ready to go.
And as for the gear, I have a JR mesh jacket that works well for me. Of course JR is a rather cheap brand, but I’m only using it for the summer months down here in GA because it is also hot and humid. You can find a partial mesh jacket that has reenforced material in the shoulders, elbows etc. Although a well ventilated textile is also a good option, especially for a beginner. As for gloves, make sure you try them on before you buy them. Theyre almost the trickiest things to find a proper fit for, next to a helmet. You dont want them too tight, but you dont want them too loose either.
Anyways, good luck with your class, and dont forget to have fun!