I'm currently kiteboarding with one of the Bledsoe brand, they're good help to relieve very similar pain you're dealing with. Have them measure your knee/leg to proper fitting. Worth the expense, they're not cheap.
Are you freaking kidding?
You arrived to a place with no other kiter? oops no kiters no pumps.Do not depend on others.
The most hated kiter is the one asking to borrow a pump, period.
I'll lend you my pump if you'll give me a BJ,
Also consider trying a seat harness, lots of beginners find it easier on ribs.
As for the board size, you may go a little bigger for the light winds you have.
Go kiting