If I'm airborne qualified and I PCS in a year from JBER, what is the likelihood I get orders to Liberty?

Moderately high, but the true answer will greatly depend on how many 11B10s (i.e., 'round pegs') are available for assignment and what the "needs of the Army" (i.e., 'round holes') are at the time. As you are airborne qualified, you are a slightly different colored one, but still a 'round peg' from the view of HRC when it comes to assignments.

Soldiers on Airborne duty are managed by the Airborne Program at HRC, so the first pass will be to maintain a high rate of readiness at the five Airborne IBCTs in the Army (three which are at Fort Liberty). However if there are more 'round pegs' than 'round holes' available, then Airborne individuals will be assigned to non-Airborne units.

The biggest impact you can do to influence the process is to ensure your CONUS preferences are updated within ASK. Those preferences are taken into account by HRC for assignments, but the needs of the Army are the first priority.

I was a volunteer in the 70 with not contract, just depend of the contract you did with your Recluiter

If you want to go to Liberty, there's 3 avenues that would guarantee it: Special Forces, Civil Affairs, and Psychological Operations. Get selected to attend one of those courses and that's where you'll be for at least a year.