XRAY - Model racing cars

I've assembled my first T4 chassis complete with electronics. All that remains is to paint the body. I noticed considerable end play with both front axle end shafts so I added a Teflon washer as a shim between the outer bearing and the stub pin for mounting the wheel hex nut. Is this a 'good fix' or does the loose end play serve a designed purpose?
I also encountered restricted movement of the steering bell crank on full right turns with the graphite Lipo battery strap installed; the right bell crank arm contacts the mounting post for the strap. I had to modify the arm with a dremel tool and whittle by hand at the contact point to improve its range of motion. Do you know of a better remedy?
Thirdly, while the wheels are spinning, with the chassis on a carstand, as the steering is turned in either direction, there is a vibration and buzzing sound. I believe it is coming from the front drive belt, because it is visibly moving up & down rapidly during this maneuver. Is this normal? I have ordered the belt tensioner for the upper deck. Is there a different remedy?