What should I expect going through A school for seabee, as prior service army?

Looks like BU, so you will go to Gulf Port MS, grate place small Navy Base. I went through Navy and my A- School is still there SW. A-SCHOOL is still based off of boot camp some, you will march everywhere and PT usually in morning depending on weather and time of year. The gym is nice, Exchange is small, being prior enlisted you might be able to have POV privileges, not sure, you will get that enough at Indoc. PT is MON, WEN, Friday and Tuesday you do inspections and Thursday is all hands NCTC Muster and quarters meaning Command formation for A-Schools and C-Schools, they do awards and things like that, the CO will speak. You will watch standing duties not sure how many watch sections. Since you are Prior service you will most likely be a class leader or some kind of class officer. You are lucky because ECS (Expediatnary Combat Skills) is there and you will just go across the street for that, being Army this will be basic stuff for you, lots of shooting, this is taught by Civilians mostly SOF guys infantry and some Seabees.

Good luck and it's nice to see a cross service from Army over to us, usually other way around. Just remember there is always BS where ever you go. Do a Battalion then you will have a good chance at trying for special duty assignments like NSW and State Department and there is much more a Seabee can do vice fleet.

Been quite a while since I was in A school.....lol But you can expect a lot of marching. Not quite as bad as boot but you will still need to March to and from your barracks to school. You will still have uniform and barracks inspections, but not quite as anal retentive as boot was. Good luck to you mate!

BU2 Maier 79-83

It's an A School, so nothing particularly unique. That said, you may be going to an Army school at Leonard-Wood. Years ago, Navy and Army consolidated a number of A schools. Classes are typically mixed service. Who does what can be seen at:
https://www.thebalancecareers.com/overview-of-navy-seabee-careers-2356508