Yep, hydraulic preloader is a good choice then, costs bloody too much, but you'll thank yourself to bits if you've even once or twice tried re-setting preload by taking off the shock each time like I've done (still don't have it, but probably will buy it soon!)
Shock's high/slow dampening & rebound settings: mostly you set them straight just once, and just remember maybe 2-3 settings for each condition.
What I really like about the slow- and high speed (it's the shock's motion speed, not related to the bike's speed BTW) adjustments is I can set is soft for sharper corrugations yet have the firm planeted feeling while riding the "wavy" (slow-motion) tarmac found in me country. Or i.e. vice-versa on crossing the speed bumps (slow action of the shock, i.e. often bottoms out with a single setting shock set soft for offroad use, or too stiff set for tarmac use) etc, where it's hard to find a compromise setting with single-dampening setting shocks.
Looks complicated at the beginning, but you start with the factory settings (specified in Hyperpro paperwork that comes with the particular shock - if you go terribly wrong, you start from there again, simple) and in a couple of weeks you start going through click by click (mostly just 1-2 clicks of each setting) and learning how they change handling, comfort and "planted-feel" in various conditions (made better/or worse and adjust accordingly on each according direction). after couple of weeks "mapping" them you'll have the optimum settings figured out and usually leave them as they are. Just those rare days when you radically change riding style from every days routine you'll re-set the settings - i.e. doing an offroad course, or a track-day etc. Most wouldn't bother with those at all and keep the "average" settings, but if you're really hardcore on settings, then those extremes you can "map" out as well, write-down or remember the settings.
(I use my brake caliper's locker key to change the clicker settings btw, that simple)
Hope this helps,
Margus