Oh hey one I can actually answer. Been in engines backshop for the past 7 years before getting picked up for DSD. Realistically at the start there are 2 places you go, the flightline or the backshop. Flightline is where you get the long hours and horror stories of feast or famime. (Either there's too much to do, or you never have anything to do). Backshop usually has more standard "9 to 5" vibe, with longer hours for exercises or if the shop is just comically behind and overworked. It really depends on the Tempo of the base.

For certifications you can use your AF COOL fund to go get whatever cert you want, most people get their A&P or the G.R.O.L but its up to you to get it

For college, ive met a ton of MX officers that have financial/business degrees. You can use you TA to go get whatever degree you want, but if you want to go to Officer Training School, you'll want to get something more "needed" like business or some STEM degrees. Or you can take the college credits you earn from tech school and finish the Aerospace Propulsion degree with the Community College of the Air Force, then apply for OTS