Okay, this is how you check left to right steering. Place the car down and and do 180 half circle. Pick the car up, turn it around and do a 180 the other way. If your steering is the same, it will come out at the place you started. You do not check doing figure eights cause you're just guessing.

A couple of inches at this speed could be a foot or more at speed.

Since you're just starting out, just have fun with the car and upgrade it as you can. The worst thing a newbie can do is to try to build a race tuned Mini from the beginning.