Ok so i'm know expert as i am working on my Keezer as well. If you mean a thermostat as in a temperatur controller such as a johnson than yes. Otherwise it is still a frezzer and not a fridge. Regulators and manifolds? A regulator is necessary if to limit the amount CO2 comming out of the tank. As far as a manifold i am pretty sure you can use one for everything but it may require more work when trying to force carb a keg. ( A lot of turning off and on certain kegs depending on whats being carbed and whats being poured. I personnaly am going woth a double regulator for force carbing and pouring (more Control) Also i am getting a manifold for pouring multiple kegs.
If this lacks any sense ..... sorr i had a few