What should I expect if I reclass to 35S?

IF you are able to reclass to 35S, you will go TDY enroute to you follow on assignment. You'll find out what your follow on assignment is 120 days prior to the start of the course. Your future branch manager won't be able to help you because the assignments are handled by the reclass team.

Issues you will encounter:
1. Assuming you already meet the line scores required, you still have to have a centrally granted (not locally granted by your commander) Interim TS/SCI before you can request a class date. Because there is no reason for a 92F to have a TS, you will have needed to have started the TS application some time last summer to have it before April.
2. 35S is a very small MOS with very few class seats. It might be months before one pops up. You may see one pop up and someone else take it on the reenlistment side before reclass team locks you in. You may want to look at including other MOS's in your request like 35N and 35P which are still signals collection.
3. Be prepared to wait. Unless someone drops out of Basic training and that opens a short notice seat, the class dates are all going to be for FY21. If you don't get one soon enough and they are all sold out, then the next class seats won't be till FY22. That means you'll still be in your MOS getting promoted and advancing as a 92F. You'll be leaving an MOS with easy progression and moving into one with much harder progression. If you aren't going to school right now you'll be behind your future peers and your promotion to SSG as a 35S will be years behind what it would be as a 92F.

Unless you’re promotable I’m pretty sure branch won’t do much for you other than tell you where a 35S can be assigned. Which are very few locations.

If your clearance is good to go you can expect to do your job and if not expect to work in the orderly room or another admin shop until you have your clearance.

Shift work is always possible with intel

Any other specific questions just ask away

Units differ from one to the next, so there's no telling exactly what you'd be doing. Shift work and normal day hours are possible work schedules depending on mission requirements. If you arrive and your TS hasn't been adjudicated, then prepare to work an administrative position until your investigation is complete.

I noticed in the comments that you're looking at other MOS in the 35 CMF. If you are looking for something technical, go 35S. If analyzing data is of interest to you, go 35N. Or if you enjoy learning different languages and applying that to a problem set, go 35P.