I can you help you some....
"1) is it safe to connect the wire for the lights in the gauges to the dimmer switch on the dash? i want the gauges to come on with the dash lights but i also want to be able to dim them on those long night time trips. "
When I had my Sunpro Tach. installed they ran the wire to the parking light dimmer, it is fine and wont damage anything and the tach. does dim when you turn the parking light dimmer.
The tach. does come on with the dash lights because the parking light dimmer turner thing is lighted.
"3)what is the best way to ground the gauges? can i do the same as the wire from the dimmer? ( connect all the grounds together and run them all to a single grounding point or do they all have to have an individual ground wire?)"
Ground the to the chassis by drilling hole in the firewall, find a bolt inside the car to ground them to as well.
By the way did you find the PCM lead wire for whatever your guages are for?
