Welcome to the Forum. Valve cover is an easy fix. Just remove, clean and seal with gasket sealant. A woman can do it . Rear speed sensor, not sure what you mean. Tire pressure sensor? Can be found on Ebay which is a good place to looks for used parts. Also a lot of Mercedes parts are cheaper than the chrysler parts. Number3 and 4 I let someone else answer. Number 5, Paul Diguer just posted a great video on the Chrysler Owners page on Facebook how to do the fix.
Join in the fun and enjoy your car. It's a great car with little problems.
Inge