I bought mine directly from doetsch. I'm not sure what info you're looking for, My set-up is just (4) 36" coil-over shocks working independently, when a shock compresses the oil just flows from the top of the shock, to the bottom, then back again on rebound. (like any other shock).
You have to land on all 4 tires to spread out the weight on a landing, so front to rear, and right to left balance is important. Along with some good bumpstops.
I haven't seen a truly hydraulic suspension, I've seen the High pressure gas over oil shocks like the monster trucks and some desert trucks use, but I was told they arn't working good for crawling.
To be able to adjust the weight bias you would have to be able to move the drivetrain or wheelbase around...To have a weight compensating system would take a computer and a boatload of sensors/valves/lines and such.
Coil-overs are what you want for a pre-runner, they are sweet, I'm finding that the harder I hit the rough stuff, the better it rides, and the easier the suspension eats-up the bumps. (like a big a** Quadrunner) : )