Coil Spacer question

I've never done spacers before and have a few of quick questions. I need to level out my LJ to compensate for the winch and bumper.



1. Are any spacers better than others?



2. Where should I measure to know what size spacer to buy (right now measuring from the bottom of the fender down the center of the wheel, my front is 2" lower than my rear.)



3. Do I need to change anything else when I put the spacers on, bumpstops, shocks, etc...



Thanks,

Tony