Good to see your hitting the track for the first time. You will love it.
When it comes to "what will break", it a pretty open question, that really comes down to how it was built and put together.
Saying that, if all components are working and the car is built well, then I would prob say the T50 gearbox would be a medum risk item. What clutch do you run?
Are you still running the ADM S series diff?
If you come off the track hard, you may want to take some spare tierods.
Eitherway, treat it as a learning experience, and have fun.
Let us know how you go.