Under the lid of the engine you'll be looking for a yellow wire that dissappears under the flywheel. It will likely be in a mini loom with another yellow and possibly a black. It will be attatched to a small lump of plastic with 3 terminals, the third one probably being the red wire that will eventually head forward to your battery (there may also be a black wire on a fourth terminal). You may find there is a grey wire already sharing a terminal with one of the yellows, that Grey will also head forward to the remotes. (if it's there)
If you have a random length of cable dangling out the remotes, it's the Grey you want on that. (assuming of course you have Quicksilver remotes to match the engine)
Can't help with the trim guage wiring or the max RPM, but 5500rpm is usually a good starting guess! I'm sure someone will be along later to help there.