Is going to school and re-classing to a different MOS considered a TDY or a PCS?

It really depends on the course. Courses that don't produce an MOS and return you to your unit are usually TDY. But courses that produce an MOS and an follow on assignment are usually a PCS. An example of this for me would be my Captain Career Course. I would PCS to Fort Benning for 6 months and belong to the School. When I finish the course I will then report to a new unit. The reason why this happens is that when you are TDY you still belong to your original unit. There really isn't a reason to do that if you are not going back there. Plus you could imagine the nightmare if you needed some admin stuff done.

You’ll be in barracks more than likely. Long term reclass schools they’ll have barracks set up. You’ll receive a meal card and lodging.

180 days normally I thought is a PCS. Billets should be provided

I just recently went through this course it is a PCS and unless you bring your family you will be in the barracks.

It'll be TDY. I released to 35G about 8yrs ago. You'll be attending training at FT. Huachuca, AZ ...in what they call the MOS-Transition or MOS-T barracks. Let me know what other questions you have. [login to see]

The reg states that if a course is 20 weeks or longer, then you will move there in a PCs status. If it’s less, it’s considered a TDY en-route school.

The ATRRS instructions will have that information.

If it's 6 months long it will be considered a PCS move. If the class has more than one phase it will be TDY enroute to the first phase with you PCSing to the second. I don't know off the top of my head if 35G has more than one phase. 23 weeks and longer is a PCS length school. You'll be required to get your own housing like any other PCS.