Generally, rack and pinions last a very very long time. usually longer than the rest of the car. however, the ball joints, the bellows boots, all the related hydraulic parts, etc etc tend to fail with age.

It sounds like the symptoms you're describing may have something to do with your alignment when the car is in motion. dead/worn/completely torn bushings do funny things on the road that they dont do on an alignment rack with the car not in motion. if the tech said you need new shocks, then this can also contribute to the symptoms you've described.

as for the turn signal, that has to do with the stalk itself. the turn signal cancel (as many call it) wears out over time. theres no quick fix (that I know of at least) other than replacing the whole unit.