WP shock help

[chillyman0]

Anyone know much about these old WP shocks

The one on my vfr is the same as the one in this link..

https://i734.photobucket.com/albums/ww348/amcq46/IMG_012806IMG_0128.jpg

Supposedly it has adjustable preload (I understand that), rebound and ride height adjustment

So the black ring at the bottom (left side in picture...has about 15 clicks when turning by hand) is this the rebound?

What is the small cap head bolt far right all about?

Finally, the ride height adjustment, is that the threaded end on the left meaning that its gonna be a bitch to adjust?

Ive never really paid much interest to shocks so dont really have much of an idea, any pointers would be helpful

Cheers
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preivious : 2007 Skyjet 125 (died), 1991 gsf400 (problems, rotting in garden)
1996 gsf600n (sold)
current : 1996 VFR750 for sale, PM for info! 2000 E1 ZX-9r