Hi
I've quit using electric motor cleaner because I noticed that the o-rings swell when the cleaner gets to them.
I've also discovered that the "bleeding" of the shocks by opening the "bottom" of the shock isn't necessary. You can either place the bladder on the shock body first or mount it on the top cap before you screw it on. It's just that the rebound is quite sensitive of how "deep" you push the bladder into the top cap before screwing it in. If pushed all the way into the cap there'll be way too much pressure inside the shock. So rather place the bladder on the shock body. Just be sure that the side flanges of the bladder aren't too big, or you might have trouble screwing the top cap on.
Anyhow, once the top cap has been screwed on the rebound should be just perfect, it should be easy to push the piston rod into the shock and once released the rod should slowly extend to its full length. This is how I've built my shocks (with the foam between the bladder and cap) and (after a little practice) the rebounds turn out equal every time!
Regarding the oil bleeding out the bottom; I'd say it's just some oil trapped on the outside of the shock, in the slots for the "shock tool", during assembly. The oil leak "through" the o-ring is minimal, but it keeps the o-rings "slick".
Sincerely, Sebastian.