If you're going to do the fronts yourself, you should be sure to find the appropriate spring compressor to keep the springs from letting loose. As far as I know, there are only one or two brands that will work on the car, none of the other brands are robust enough to safely secure the springs.

A good way to test the shocks is to find a wavy road, or one with some dips in it, and drive over it at moderate speed. If either end oscillates up and down much, it's probably time to replace them. I think the W124 shocks last a good long time, 200-250k miles, so it may be time to replace yours.