Read this
http://www.aa1car.com/library/wheel_alignment.htm
Poor wheel alignment. Might want to take it in to get realigned.
Shaking at speed - probably due to poor wheel alignment or wheels needing balancing
steering stop fell out on one side or poor wheel alignment
Four wheel is preferred.
wheel balancing is to balance four wheels. wheel alignment is to straight four wheels.
The shaking might be due to wheel imbalance and the pulling due to poor wheel alignment.
Yes, wheel alignment machines do need to be calibrated.
A wheel alignment is what syncs your steering wheel with your wheels. It ensures your car will drive straight when your steering wheel isn't turned.
if you have independent suspention front and rear chances are a 4 wheel alignment can be done typically front wheel drive vehicles but not all.
An alignment tech.An alignment tech.
Before-a bad alignment cannot "unbalance" a wheel, but an unbalanced wheel, if bad enough, can throw off an alignment.
A two wheel can be done, but a four wheel is preferred.