That really depends on the MOS, the Unit, and the state you serve in. Ironically Soldiers in the Guard volunteer for deployments because it qualifies you for more benefits like the full GI Bill, Haslwood Act, and the VA loan. You can also reenlist overseas and get a tax free bonus. There's other good reasons to go as well.
That will happen at the Military Entrance Processing Station once the applicant's ASVAB scores are confirmed and they're physically qualified. The applicant will know what they are receiving and in what distribution prior to taking the oath and swearing in.
You only need a 50 or above to qualify for the bonus. You can be an 11B with a 31 or above, but anything between a 31 and a 49 does not qualify you for extra incentives like the bonus or the GI Bill Kicker.