On my audi the speedometer doesnt work and the dash light doesnt

The speedometer problem is common but not super simple. Jarring over the years has caused solder connections behind the gauges to come apart. Depending on your skill and desire; the cluster must come out and often it's just as easy to find another (I believe Audi 200's of the same era are identical, but not quite sure ask Shokan) and replace. Smoke is blue - most likely oil, meaning rings or valve seals or possibly other internal oil seals causing blow-by. White sweet smoke is the usual antifreeze correlated with head gasket leaks. Seat warmer....have fun.

Speedometer problem: This is well-documented on V8 and 200 models..Check here for info:
http://millerfactor.blogspot.com/2008/05/1991-audi-200-turbo-quattro-and.html

Dash lights: check the dimmer control knob first, then the bulbs..If not those, then it could be related to the problem above...

Driver's seat warmer; could be broken wires leading to the warmers inside the seat from, or the elements are simply burned out.

Blue smoke is oil related, not head gasket (which would be white)..Most V8's will exhibit a little blue smoke from time-to-time, but if it is excessive then it may be time for vailve seals or piston rings..depends on the mileage.