I've got some suggestions for two of your problems.
Dash Lights.
Do your other lights work, i.e. the glow in the fog, demister, etc.?
First, if you have a fader switch on you headlight buttons, just move it round, sometimes if it's right down you get no light.
If that's fine and you actually have the fader switch, pull your headlight switch, and check that the contacts are touching top and bottom.
If that's all fine, then it's either the wirings, or the bulbs in the dash, your going to have to remove, a long job apparently.
Trip computer.
Pull the fuse out and leave it out overnight, this usually resets the trip computer.
Heater, have a check the other posts in this fourm, you might find an answer.