Suspension is not my forte', my limited knowledge of suspension physics was picked up while playing Gran Turismo 3, so not very bike related anyway.
So I'm looking to tinker with teh suspension setup on my '99. I bought it as is, it came with Eibach rear suspension, and stock fronts. The previous owner had both from and rear adjustments up tight.

I found that the bike would lose the road when going over speed humps and potholes. I've given both front and rear a few twists with the screwdriver and and eventually found a mediocre harmony, but currently the handling is slow, and the bike still gets a little upset when hittinh speedhumps and poor road surface, naturally most predominant when in mid corner.
I've read some of the articles here and I gather the first step is to set the sag.
So my first question is:
-When measuring the suspension length, should the bike be on the centre stand or sitting nauturaly under its own weight?
-I assume the sag adjustments are made by the little screw on the rear shock, and the screw on the top of the front struts?
-I understand that you can adjust the rear spring, on visual inspection, there doesnt seem to be any obvious way of doing this on my bike, so how can you do this and what will the affect be?
-What other adjustments can I make to customise the suspension settings?
Thx.
Rob