I have had all these problems - battery running flat, smoke from the dash and the dodgy rev counter. Managed to fix 2 of the 3.
1. BatteryTried swapping the battery with another and it was still going flat after 3 days or so, even if i left it running for an hour or took it for a long drive to charge it up. The issue was the alternator belt was slipping so the battery wasn't being charged properly. My local mechanic came over and took a look and said you shouldn't be able to turn the metal disc attached to the alternator with your hands. If the alternator disc is slipping the battery won't charge properly and the battery will keep going flat. Had the belt tighened, gave the battery a full charge with a charger I bought off eBay for £15 and it has worked fine ever since (probably half a year now).
2. Smoke from steering columnTook off my steering wheel and both of the stalks. The indicator stalk had cracked. I could see that the plastic had melted and where there was a crack there were scorch marks on the steering column. Bought a new stalk off the forum for £15, fitted it. Job done, no more smoke from the steering column.
3. Dodgy rev counterStill working on that one!

Like I said, these are just the problems/solutions I came across for my own mk2, but both are easy enough to test out for yourself without a trip to the mechanic so may be worth a look.
Hope that is of some help,
Dave.