With regards to the caliper issue, often times, calipers are fairly cheap to replace. It is best to get a new caliper than to rebuild the old one. make the call on your own.

Note for the future, this is exactly why it is SO important to flush and bleed your brake system as regular maintenance. Every two years at a minimum. Even if the pads are still fine, the system needs fresh fluid.

best of luck.

__________________
85 300D 3 pedal. Current project.
83 300TD (need rear wiper assembly dead or alive)
84 300SD Daily driver
85 300TD almost 400k miles and driven daily.
98 E300D *sold
86 300SDL *sold and made flawless 10 hour journey to new home.