Can you become faster by working out your legs
It always starts within. Having healthy heart, lungs... You can strengthen and become faster. Without the two, it wouldn't necessarily make you faster but you'll have strong legs.
Yes , and it will help you jump higher
Yes.. Different kinds of works outs help different thingd
The more you run, the faster you will become. Run Forrest, run. Apologies, it's 4:46 am and I have been here way too long :-).