The first one is trivial - the wipers no longer "retract" back under the bonnet when not in use. Is there a switch or connector I can check? It sounds like a ground issue maybe?
I have the same problem with my current ('91) 164. The wipers seem to rest at the 'put away' position on every sweep, and when I turn the wipers off, they go to the same position.
On my '92, I remember watching the motor (cover removed) and noticing that for the final 'put away' sweep, the motor reversed direction.
Do you get the final sweep, i.e. if you turn the wipers onto intermittent, let them wipe once, and then turn them off, do they make another sweep? Or do they just turn off?
I'd be interested to know if the motor reverses, too. I was thinking about this and I reckon if the crank arm was attached to the motor at slightly the wrong angle, the reverse sweep wouldn't be any longer than the usual forward sweep.
I'm still not sure why the wiper is designed this way... on my '91, it means that with the wipers set near the bottom of the screen at rest, the driver's side wiper doesn't get anywhere close to the vertical edge of the windscreen - which is dangerous when approaching roundabouts. I almost wonder if it's worth trying to make a longer crank arm for the motor, to get a bit more stroke at the arms.