I hope Jimmy have cellphone, motorbike, parachute, body armor, gas mask, his own locker to store weapons and money, his own garage, and Jenkem lab.
It's also OK to make Jimmy athletic, fat, or both. If he's both fat and athletic(like Heavy from Team Fortress 2), he can inflict and resist more damage but he will be slow moving. Also, the fat nerds should be tougher, at least like regular prep or greaser. Also add more tough fat kids for Preps and Bullies(Greasers already have Hal, and Jocks are unlikely to be overweight).
I like the disease system, If you fall off or taking much damage on feet, you will break your feet thus you moves slowly like in Firearms. Also, infections like cold outbreak once for a while will makes everyone not protected by gas mask weaker and shut down classes for 3 days, and Jenkem infection so everyone not protected by gas mask hit by Jenkem's blast, poop shrapnel, or jenk gas will vomit, takes damage over time, piss on themselves, and eventually poop on their pants or end up unconscious because of blood poisoning. All infections mentioned above are contagious by touches and short range talkings.