I am enlisting in the Army after 4 years active duty USMC, during which time I was a 0651 (equivalent to a 25B, and I also have the DMS addon if any of that stuff transfers over). I was wondering because my recruiter hasn't been very helpful, would it be better for me to stick with the 25B MOS, and if I do would I still need to attend AIT? I have also spent the past year and a half working for an IT company and keeping on top of my skills. But I read up on 25S and think it sounds like a very interesting MOS.

The main reason I ask is that I have a specific unit in mind that I'd like to go to, which is the 58th Signal Battalion, Fort Buckner, Okinawa, Japan. I don't mind doing Army AIT and in fact welcome the exeperience, but I'd like whatever route I choose to lead up to getting assigned to my "dream unit."

1. Do any of my previous MOS qualifications/experiences count to anything?

2. How are units assigned when a prior service soldier joins the Army?

3. Would I be assigned a unit and THEN go to the unit and then to AIT, or would I go to AIT and THEN to a unit?

Sorry for the text wall, but that's the rough idea of what I'm asking.