I drive an e46 myself and during the cold/wet weather I experience the same fogggy window thing. What I have done to solve this is very simple.
1) I close my center vents, open the two outside vents and aim them right at the window, I then select the top two blower features (directions), top windshield vent and middle or dash vents ( I do not use my front window defrost button at all since it takes away from the dash vents). If you want feet too knock yourself out. This has solved my issue for the most part say 90%.
2)It is not stronger than most or weaker, drive reasonably and expect obedience
Obviously abusing the clutch will result in the same repairs as any vehicle.
3)Common, glass can be replaced yes.
4)Seats are base I assume, a little flat and stiff for ya, I agree. Sport seats are nicer of course BUT narrower so if you are a big guy you may not like them.
5) I have no clue about this area, not a big radio tech guy
6) Most e46's share the same group of common issue you will run across. Non what you would call major per say but here is a short list.
-Vac. leaks ( Usually from intake elbow(s)
-Oil Housing Filter Gasket Leak
-Power steering line leak
-Valve cover leak
-Brake sensor (not that common but can need replacing from time to time)
-Cooling system (Rad hoses, plastic elbows and resevoir like to leak from time to time)
-A frame bushings (These can be pressed out and in by most good bmw shops, if I recall the dealer will not do so and force the purchase of a new arm)
-DISA valve (Not that big of an occurance but I see it time to time, it is the small box located on the intake side of the to manifold, it directs air flow to runners)
There are maybe 2-3 other common things but just about any e46 owner who has driven his or her car 100,000-300,000+ kms has likely experience a large majority of the above at some point.
Other stuff like brakes, shockers and wheel bearings can be expected but more so as you would expect.
The only major issue I see is over heating and continuing to drive. If you over heat STOP the car. You blow a gasket, warp a head etc it is motor out time!
Lastly for the love of god change the oil every 10000-12000 km's, the 25000 recommended is obsurd!!!!!