Since no one else has answered your questions I will put my 2 cents in. The easiest and some say worst way, is to simply take an angle grinder and lop off a loop from the coils. This will drop the front end down, but will give you less travel in the front end. I lopped 2 coils off, dropped the front of my '63 about 3 inches, but even with the snubbers cut down I only have an inch or so of travel. *note* you do have to take the springs out to do this and don't use a cutting torch.
Altho it costs more the 'proper' way is to put in dropped spindles. In effect the spindles are raised up from stock, thus lowering the truck. Then you can use your original spings and have the proper spring travel. Nothing else changes. If you want to 'drag frame' then you add lowering spings and even different 'A' arms that allow you to go even lower. By this time you might as well get rid of the lowering springs and put in air bags so you can get decent ride height on the hiway and then drop it to cruise the main drag.
It really depends on what you want to do with the truck and what your budget is.
Sorry can't help you with the car spring question, but I know the softer the spring the more it will compress under the weight of the truck. That may give you a drop in the front end.
I haven't done anything with my shocks.
