I am no Nitro expert, but I can shed some light on your questions
regular 2 channel radios are actually the rules, so whatever you use for 10th scale will be find for 8th scale, possibly even your servo.
it is just a steering servo as normal and a servo in place of your ESC to operate brakes AND throttle
10th scale reciever is perfectly fine
Everyone doing 8th scale would be more than willing to help you out, go to a meeting ask a few questions to people and I am sure you will find a PB to lend a hand, you might have to return the favour for them, but it all ends up working well. there are other people in the same situation as you are.
with regard to engines, if they are tuned right, they are reliable, its not an easy thing to learn, but there will be plenty of people at a meeting or a praccy day that would be willing to tune your engine to get it running good for you.
from what I have seen going to practise days and stuff, 8th scale racers are always more than happy to lend a hand
