Yes, it just screws in and yes it has "O" rings. They are easy to replace. However, you will want to release the pressure to it, by unscrewing the middle screw on the back of the soleniod. You only need to gently loosen the screw until you hear the fluid be released, normally a couple of turns out will do it.
The "O" rings should come out with the unit, if you carefully remove the unit. Before replacing the unit, you need to make sure the "O" rings did come out. You will also get some hydraulic fluid leak out after removing the solenoid.
It is not real common for these to leak. Could just need to be tightened up.
Monaco 2005 Dynasty & Arctic Fox 996
FullTimers with Cats: Zippy & Sami (RIP)
Honda CR-V chases us everywhere we go!