You (kicking team) can catch it in the air after 10 yards wither it hits a player or the ground or not.
Actually, under NFHS rules, you cannot. It is ruled "kick catching interference". The ball MUST either: 1) touch the ground, or 2) touch a receiving team player before K can recover. If ball strikes ground and travels 10...well..we know, live ball. If "R" touches ball before it goes 10 yds (either in air or after ball has hit ground), live ball. If ball travels in air beyond 10 yds from free kick line, then it must strike ground or an R player before it can be recovered (note--it cannot be advanced).
It is an oddly named rule, b/c it implies you must interfere with catch, but, in reality, you cannot run down and catch the ball.
It's rule 6-1-something...do not have rule book w/ me.
Also, on free kicks, you can only place kick or drop kick on a "kickoff". Punting is only allowed following a safety (edit).
"First touching" applies only to a member of K touching the free kick in neutral zone, before it travels 10 yards.
Note that R's free kick line is a vertical plane, like the goal line, so if in some wierd circumstance, where ball struck ground in neutral zone, then passed R's free kick line (i.e., it traveled 10 yds) in air and wind blew it back, it's a live ball that K can recover.