My car literally has/had all the issues you listed in the OP lol. I use Meguire's Gold series wipes for my new dash and seats, they clean and protect your leather and leave it with a nice shine for quite some time. I have the lock problem as well but thankfully its on my passenger door, it's got its moments where it would work, but that doesn't happen very often. Not sure if you're aware but you could also unlock your doors from the trunk on our cars which might be a little easier than walking to the other side of the car lol
1990 325i Sterling Silver Metallic/Black leather.
M52B28 OBD-I W/ S52 Cams, M50 Manifold, SS Headers, Kamotors v5 CAI, Stage 2 F1 clutch w/ 14lb chromoly flywheel, Mark D chip tune.
Bilstein Sports with H&R Race springs + E90 drop hats, F+R Strut bars, '04 330ci Steering rack (3.0 Lock to lock, 13:1), 3.15 Z3 Torsen LSD.
Custom Built BBS RS's 16x8 square.