As far as weight training to increase jump distance, I would use squats, dead lifts, olyimpic lifts etc. those focus on the fast twitch explosive muscle fibres that affect sprinting and jumping. Many of the wolrd record holding deadlifters can jump over people. Heres a link to some articles that will outline how to jump higher.
http://www.bodybuilding.com/fun/bbinfo.php?page=VerticalJumpthis article has a good list of weighted excercises to do
http://www.bodybuilding.com/fun/softball15.htmthe higher you jump the longer you're in the air, the longer you're in the air the farther you can jump.
Also having huge legs won't prevent injury from falling greater heights, that has to do with how you land and your bone density (which should increase as you increase strain on your legs )
Try doing box hops, find a step, a box , a ledge or similar at a challenging height and just jump up onto it, then hop down. lather, rinse, repeat. Try to do it at a quick pace, but focus on technique over speed.