And what is the cause given by shop for steering not centered.
And what equipment is the shop using? And what procedure are they following?
If they straighten one wheel and align the other and undo the steering wheel to straighten it, find another shop as this one is garbage.
If they cannot dial in rack center first or even know of it, find another shop.
Wheel bearings causing pull is mixing symptoms with cause, as a dragging brake can cause pull which manifests itself as a hot wheel bearing.
For reusing coolant, if its oily, you will have to let it settle for decanting later on, if its gritty then you need to filter out the particulate matter.
If its really old coolant and engine has been cooked once or twice, its probably done its life. Best fill new coolant.