yes, you want electronic. mechanical is more accurate but a bigger pain in the ass. with electronic you just tap in to the correct wire. with mechanical you have to tap into the object you want to moniter. and then its best to have the gauge outside the car on the hood
The CF Ultra-lite gauges are really nice. Just do us all a favour and don't get them for bling-bling only, and don't buy gauges you don't need. If you don't NEED them (ie. Forced Induction, NOS, high compression ) stick to water temp and oil pressure.
The stock water temp isn't very accurate, and the stock oil pressure isn't that great either. By the time you see the idiot light its usually too late. These two gauges will give you a better chance of seeing a problem before it becomes critical.
Electronic are better for street cars due to safety. For example, a mechanical oil pressure gauge actually runs oil to the gauge. Do you really want hot oil flowing through your instrument cluster???
Mechanical is really for race only cars in my opinion.
Full sweep means the needle sweeps all the way from teh lower left to the lower right of the gauge. Kinda like your speedometer.
Gauges that arent' full sweep often only have the needle move through less than half the guage. Your stock coolant guage is an example of one that is not full-sweep.
Here's what the CF series looks like. As far as what gauges you get and whether you get mech. or electrical, that is totally up to you. My oil psi guage is mechanical, and i've got no problems with it what-so-ever. If you're careful with how you install it, you'll be fine.
I used copper tubing instead of the nylon tubing that autometer supplied because there are stories of the nylon busting. I didnt use a Tee fitting for the oil pressure, i just unscrewed the stock unit out and screwed in the piece that autometer gave me with the copper tubing attached.
accuracy wise, mech and electric are very similiar. you won't be able to tell the difference.
reliability wise, i trust mechanical more than electric considering you have a better chance of something leaking under the hood and causing damage to the little sender than you do of the high-test nylon tubing from bursting in the cabin. assuming proper installation, of course (aka, not expecting the nylon to turn through a 1" radius circle, and not being kinked during install). and they're cheaper.
they've also had many many more recalls on various electronic gauges for the reason above--never see recalls for mechanical gauges. (say, fuel pressure senders leaking, so then you have fuel going over electronic doo-dad's... or coolant temp senders leaking, and then you have water going over eletric sender... etc)