Car wash causes a little drip. That is not from the rear drains, it is because the seal around the glass roof is rusty and allowing water to go through. There is NO easy fix for that, although I did replace my roof glass from a 1998 to stop the leak. Pick & pulls are great for that. A V/S70 1998-2000 will work, but it is best to inspect it for rust before you buy it.

The rear drains cannot be seen with the headliner off. You can see the drain tubes as they pass through the rear tire wells.

The sun roof sticking is usually due to debris on the tracks. Or a plastic piece has jammed itself. I would take off the sunroof, just 4 T25 crews, clean out the tracks without removing anything else (do not expose the cables), and run the motor back and forth. Sparingly use either lithium grease or some other grease and coat the sliding surface, do NOT spray a bunch of lubricant on it.

Actually, $175 is a pretty good price. The DIY method requires 2 days, and it is not a lot of fun!

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Keeping it running is better than buying new

Geeze, that's a hell of a deal.
Are they removing the headliner to replace the fabric? I kind of doubt it for that price. I did my 745 twice. Absolutely the most dreaded job I've ever done on a car. It did come out very nice (the second time!), but it just wasn't my kind of car repair.

Hopefully you can post back after it's done with the results.

As for sunroof lube? I'd use white lithium but would first try to identify what the factory used. Be sure to clean all the old lube out before relubing.
I probably wouldn't goop it on either to avoid trapping sand and dust in the lube.

This is a perfect time to inspect the drains for the sunroof cassette.

The rear drains tubing is found by the rear tire wheel well, just next to where the antenna is on the cars. You have 2, right and left.

If the windows do not retract try to clean the junk with a leaf blower and inspect the tracks and add some lube.