I had the same questions when I was to replace mine. But STEVE*** told me not to worry about it.
I replaced a pair of shocks, and the accumulators (spheres) then just top the resevor with fluid. I also jumped on the back bumper up and down for a few minutes, then took it for a hard country road with lots of bumps. It works great right now. I wish, I had them replaced long ago.
If you need to adjust the height of the back, I suggest you should wait a few days.
Have fun and don't worry.