W123Leak and door problems

[seattle240D]

Hello guys, its been a little while but I'm back to ask the gods for some wisdom...

I have a 1981 240D. About a month ago (after some serious winter stormage out west in Seattle/Vancouver) I noticed my rear right floor mats were soaked through. Like standing water in the car. But ONLY the back passenger side seat. The front passenger floor is damp, but it sometimes dries out during less humid weather. The rear right side never dries out- even after I vacuumed an inch or two of water out of the floor, and a few more out of the mat.

The other problem (hopefully linked?) is with the rear passenger door. It has been making a creak/cracking noise for a while now. It probably just needs some grease, but the other night a friend opened it a little hard and it was almost impossible to shut. I thought it was seized at first. Is there anyway water could enter the car through the door, affecting that funky hinge, perhaps? I haven't noticed any rust spots on the right side of the car so I don't think its getting in from the bottom...

The other idea I got involves windshields and glass seals. I just had a new front windshield put in (due to possible leakage in the old) but the rear glass is old. Furthermore my trunk has been damp for some time and I've noticed drips on the plastic wheel well lining as well as condensation inside of the trunk (sometimes frost). Is there any way the drainage gutters could be leaking into the trunk?

I drive in the rain a lot between Seattle-Vancouver and Vancouver-Whistler so my car doesn't get to hang out in the driest of climates. Gotta get this fixed...among other things, haha

see ya soon!
Thanks for the help!

1981 240D 328k "Sexy Cede"