The other way to think of preload is that it now takes x pounds of force before that spring starts to compress any more, but once it achieves that force it will roll more based on the spring rate. Example, 300# spring with 350# of preload will take 350# of force to start to move and then compress at the rate of 300# per inch of spring travel. Whereas a 350# spring would require more weight transfer for the same amount of roll.
Droop limiting increases the amount of weight transferred per degree of roll once you hit the limiter. The inside spring no longer is able to assist in raising that side of the chassis and you now have to lift the whole suspension.
There are different types of limiters as well. I do it with a spacer inside the shock, but also have a cable set up that allows the car to still roll to allow the roll rate to remain consistent. I used to run an external limiter but for whatever reason it would never stay consistent.
Keep in mind this is on a pushrod car not a rocker.
I think the best advice has already been given, KISS. Set the car up with no droop. Use the spring perches to set the ride height and drive it. Once you feel you have maxed out that set up, try the limiter and see what the result is. Trying to engineer the car before it even hits the track is a sure fire way to get it all screwed up. Both preload and droop limiting are tuning tools that have both pros and cons. You as the driver have to be able to judge if the benefit out weighs negative effect.
John