I agree, the 5T will pull your hair off in a B4, most of us will only run 5.5T in 4WD buggy, and that can be very quick with the correct gearing and battery. Good comment about your EPA adjustment, trim it down low on your throttle and it will save the wheelies and bald back tyres until you get the hang of it
ESC is best approached by investing in a good quality second hand one from a trusted oopler, as suggested check out the for sale section, people are generally very helpful so don't be scared to ask about spec you don't understand
Most importantly, charge your battery and go have fun, its an amazing hobby...you won't regret it
Best of luck