How soon can I reenlist? And could I have a bit more say in my contract the second time around? (ARMY)?

John is completely right. You would get PRK and be on a waiting list. Since you are Combat Arms you are priority 1 (end of the line for the priority 1 list but you are still going to get it faster than all the other MOS). You should be able to have that already done and fully recovered by your 3 year mark. Once that happens try for a recl of MOS to go Infantry then when you reenlist get Airborne in your contract (and Infantry if you couldn't get it earlier). Once you are a SGT with the Infantry go for SF. Thanks for your service.