You'll want to check the caster settings for the issue with the wheel returning to center. Too much positive caster and the wheels won't center without assistance.
The rear end moving around is a pretty common problem. The problem lies in the design of the suspension, where the upper control arms are given the task of locating the housing under the car, but they do a poor job of it. If you really want to resolve that issue, some aftermarket control arms may help, but you're probably looking at spending some money on a panhard bar to positively locate the rear axle housing.
The rear end moving around is a pretty common problem. The problem lies in the design of the suspension, where the upper control arms are given the task of locating the housing under the car, but they do a poor job of it. If you really want to resolve that issue, some aftermarket control arms may help, but you're probably looking at spending some money on a panhard bar to positively locate the rear axle housing.