I can help with some of it.
I guess you figured out the up down orientation and the wiring goes out the starboard side as that's where the electronics are located.
Solid black wires route through the engine powerhead where the battery - is usually attached....If it's black, it is ground (batt -).
All the CDI's perform the same function. Only question is which cylinder is "ready to be fired" when the trigger gets to it. I don't have the wiring diagram but you can figure it out. Plug them up and if the engine idles smoothly (675 rpm range) and takes the throttle easily, you can pretty much figure you got them right. If not, swap leads till it happens. That's how I used to trouble shoot.
Edit: The 675 number is in the water, moving forward in F gear (repair manual number). In N it would rise up to maybe 800 give or take.
If you don't have steering torque problems (turn loose of the wheel and the boat veers to one side or the other}, you don't need a trim tab. If yours is missing, may be that it's not an issue. Smaller hp engines don't have them for that reason.....Mercs anyway.
Trim tabs are readily accessible and just look for the one that fits your lower unit/engine series; usually specified in the www ad. You'll need a hex socket stainless steel bolt to mount it. When installing, start with it straight out and if you get some steering torque, turn the rear of the tab in the direction the boat turns. Obviously, the more that it's off center, the firmer the response.
