Looks like from this Marineengine diagram, that it just disconnects via a 3.8" bolt that appears after you take the 6 lower unit bolts out and drop the LU down about 1/2" to access the bolt. The bolt is now located in between the LU and the exhaust tower. Take the bolt completely out and it should drop down. It's pretty simple. When re-installing, be sure to look with a light into the hole to make sure your holes are lined up where the 3/8" bolt came out, so you don't cross thread it and strip it. The water tube is kinda "self guiding" so should go in pretty easily, but take a flashlight and look in there upon reassembly at the last minute just to make sure it's stabbed the hole.
About the wiring, I myself am ignorant on the subject, but we have some real geniuses here on aomci that will be along shortly...
Good luck, lots of help here on aomci, don't be afraid to ask should you need further help. We are all in this hobby together, and eager to help!
http://www.marineengine.com/parts/johns ... n=Gearcase