Hello mate,
I don't know how much help I'll be, but you should definitely check your earth crowns above the fusebox as already suggested.
It's hard to diagnose these things without a multimeter and the van there, but it'd be worth taking the cowling off the steering column and checking the bundle of wires that go up the left hand side and also check the integrity of the connector - it does seem that perhaps you have a short in those wires somewhere where perhaps, and now a faulty main beam switch on the indicator unit you got. The plastic connectors can crack and allow annoying shorts to happen so it's worth looking at this. The indicator problem could also be a short at the hazard light switch potentially as current goes from the indicator stalk through the hazard light switch and to the bulbs. I'd check there.
Sounds like you might be unlucky with your new indicator stalk and main beam function....
There are wiring diagrams here which help when tracing faults:
http://www.club80-90.co.uk/pages/downloads.html" onclick="window.open(this.href);return false;
Good luck
Ewen