You will probably get a lot of different opinions to those questions but here are mine:
As for the wire gauge; I think that 12 gauge is way too big for most applications, even open mod. 14 gauge is plenty big and the new four cell brushless speed control comes with 16. So does the Keyence if I remember right.
A good servo that is inexpensive: That is almost a contradiction in terms LOL. Again my opinion, this is where a lot of people skimp when they shouldn’t. This is the thing that steers your car and a cheap one will not help you at all with handling. Wait until you can get one that is ball bearing, and has good speed and torque like a Futaba 9102. I am sure that some on here will swear by the $20 servo that they have and tell you that you don’t need anything else but the better the steering servo, the better control you will have over the car. Personally, I like the digitals but if you have never used one, they may feel “touchy” because of their higher speed and they are not necessary but do invest in a good one no matter what you get.
Rear stagger makes the car rotate better through the corners but is mainly used on banked tracks. For flat tracks, I would start with both rear tires the same size and with some experimenting, you may even find that “de-stagger” (right side smaller) will work for you and make the car drive off the corner better.
Hope this helps you.
