Link:
click it thingy for how and what a does it
hope that helps with Q1 dude.
Q2 is pretty hard to answer, its what ever falls into your comfort zone for skill and body weight.(my 9.5 depower only just flys in 7, at 13 its pulling well at 17 I put it to bed cos it's more than I'm comfortable with... but others will keep out a similar kite up to 20mph+)
Q3 never boarded dude, but its a similar technique to buggying upwind.
think sail boat, you move across the wind, to get up wind you need to tack/gybe against wind(lots of distance across wind with a little ground gained up wind on each turn)
Q4
another click it the best guide I've seen yet for jumping technique, get it right and most kites give you some air. nothing smaller than the 4.5 tho dude.
hope the links work, and maybe some better explainations come along from thems that can write what they mean to say....
Take it Easy, Yeah!?
Iain