check your fuel sending unit...if its loud and noisy you may want to replace it.
Leaking fuel injectors?
Depends on how hard you fling into, are flung onto or remain seated. Fast, faster and very slowly. "Back-breaking work" is way more than just a slogan.
sitting
get a new alternator and battery
no
It has no effect. That is nothing more than a myth.
Yes, standing up burns more calories than when you sit.
It can be many things so with our more information it is hard to say. If it has gas then it more than likely does not have spark.
traffic
binge drinking
It's really not that hard, just tell them to sit down rather than rise. and to put a little more weight into their stirrups than they would usually to stopp them bouncing so much.
More difficult than rounded instruments, yes. I wouldn't advise getting into the habit of playing them while sitting, as you'll eventually adapt to it and may have trouble playing it in the normal position. If you have a flying V, I would suggest that you play them standing up, with a strap.