Im a 25S and Ill tell you first off, if you make the decision to try this, you will PCS to Fort Gordon. The training consists of a 12 week portion of Common Core Criteria explaining the basics of the job. After the first 12 weeks, you will branch Tactical or Strategic. This portion is called AOT or assignment oriented training. Dont pay attention to that because it doesnt matter. I went through Strat and ended up at a Tac unit, but Ill get into that.
What does matter is that if you get strategic, you are more likely to end up at a step site, which typically consists of shift work and just monitoring links. Also, branching strategic makes available the opportunity to be selected for the 1C course, or "one chuck", which is the Satellite Controller course, which I strongly recommend doing if you can. It is worth money on the outside. Anyhow, the Strat course is about an extra 12 weeks added on top of the initial 12, which the potential 6 months for 1C if you get it.
Tac is about the same and will consist of using different equipment. When I went through Tac classes trained on 85D vans and the Phoenix terminal. Afterwards, they had a VERY brief 2 week crash course on the JNN which is what alot of 25S end up working with.
Now, things that may affect you assignment after completing the course are which ASI you recieve, 7E(strat) or 7D(tac) however, I have a 7E ASI and because I went to Airborne school, ended up at a tactical unit. It matters to an extent which one you have in terms of where youll go, but usually around the end of Common Core, you would get your "projected orders". Mine were the only ones I saw change from then until the end of the course, but I was kind of a special case.
I will tell you that the 1C assignments are non deployable units and are only at I believe 7 step sites around the world. I know Japan, Hawaii, Fort Carson, and Landstuhl Germany are among those sites.
Hope this helped a little.