Replace them in pairs. If you replace one front, replace both. One rear, both.
You don't have to but it is recommended and a good idea to.
bad idea- just buy lowering springs. it's alot safer for everyone!
The coil provides the extra power needed for a good spark, without it, a weak spark may or may not ignite the fuel/air mixture. It's a good idea to replace the coil every 50,000 miles, or every time you replace the distributor cap and rotor.
Replace all rubber bushings, install new shocks, replace all worn hardware (bolts, washers, etc and probably a good idea on a 30+ year old car anyway) most noticable difference will come from installing a new set of coil springs. Be careful when ordering springs, most "performance" springs will actually make the car sit lower than the factory height, thereby completly defeating the end result you desire, there should be a few places where you can still get the original factory springs or exact reproductions. Good luck!
I like the air suspension myself but you can change the fronts and rears with springs and struts for around $400.00. There are a couple of people selling the replacements on E-Bay. They are fairly easy to change, can easily be done in an afternoon.
If one of the three coils is no longer firing then replace it. It might be a good idea to go ahead and replace all three, if one has gone then the other two might be right behind it and also fail.
It is a good idea to replace them at the same time as your regular tune-up.
It is a good idea.
I believe this is a trick question. I'm not familiar with a single model of Caravan, Town & Country, or Voyager that had leaf springs. They were all designed with coil spring and strut suspensions. If a Caravan had leaf springs it would be a bad idea to drive it with one broken, unless you want to scrape your undercarriage off on the road.
Good idea to.
Selling mattress springs that have been stripped down is a possibility. However, this is not a good idea because it could hurt someone. It is not illegal, though.
Is it good idea to replace acid and water in batteries