Try some searches on the matter. There are posts on this site with links to numerous suspension sites explaining the whole process...how, when, why, etc. etc. Some of the older listed links may have changed. You might try motolinks.com (valid URL not listed for a reason) to find all sorts of links to services, parts, information and such.
Briefly, a couple of things I don't see here that are important.
re: Where you measure from/to.
It makes a big difference. It's clear that you have to measure @ 90º to the suspension action, right? Don't see that noted. Does that need explanation?
re: Screwdriver and hammer.
If you wanna. A lot less damage (read: none) if you loosen the lockring with a drift (screwdriver if you must), then adjust the spring length by TURNING the spring. Easy to do with bare hands. Suspension unloaded of course. ;) Helps if the spring is wetted with some soapy water. Having the frame extension rod out makes it easier, but isn't necessary.
re: sword30
Sorry...the lack of any punctuation in your first 'sentence' makes it impossible to understand. You can 'hardly touch the ground when you adjust the spring..'?...or when you '..adjust the spring it becomes bouncy..'?
No way your shock spring should be 'bouncy' at all, period, never. IF your suspension indeed 'bounces', you need to adjust either/both the compression (top) or rebound (bottom). Compression needs to be SOFT enough (clicks out) to absorb impacts without jacking your arse, HARD enough (clicks in) to take as large an impact as you're going to give it. Rebound needs to be FAST enough (clicks out) to be ready for the next impact (not 'pack'), SLOW enough (clicks in) to keep the wheel on the ground during the rebound process.
The forks are compression only (for most of us dollar impaired, don't-got-rebound-modification-$$ conventional fork slobs). First, have the correct spring, oil level, preload for your application. Then, adjust the compression so it will be soft enough to not jar you to death and feel every pebble but NOT bottom (well, maybe seldom) on the roughest stuff you ride on.
If you want your bike lower, check out kouba links. They make pull rods of a longer design that will lower your kdx by up to over 2 inches. Yes, the front does need to 'fit' this drop. Read the FAQ info. You may need a stronger shock spring in some cases. The longer rods increase the leverage on the shock. This is more often a good thing than bad. Devol makes a set, too. They are adjustable, but only to: 1. Normal, 2. One position longer, 3. One shorter. In the 'longer' position, your seat height will drop about 3/8".
re: jfrancis.. 'top shock bolt center to the 2nd lock ring'
It's as beefking said. Nothing is measured on the shock.
re: wallasaki 'over the bars'
Maybe that was due to your fork springs being 'phoof' (fluff..soft)? If the back end kicks THAT bad, you might try a few more clicks OUT on the shock compression. ...probably your front end, though.
It could all come from too much gas at the wrong time, too! If you're powering all the way over, you'll pile drive the front end into the ground.
So many questions......so little time......;)
Cheers!