I recently acquired a 95 sl500 and had much work done by my independent mechanic who specializes in Benz.

Oil pressure sendign unit is an easy DIY if you want to save a few bucks. Its right by the oil filter, unscrew old one, screw in new one, hook up connector.

3rd brake light wiring again easy, $150 seems very high. Access to where the wiring is broke is easily got to.

You should be able to get new wheel bearings for $50.

I had my engine mounts and strut mounts replaced for that price you were quoted for engine mounts. You may want another opinion.