Boat project questions

New to the forum and full of questions for those of you with the knowledge to assist. I have been given( ayes, free) a 12ft aluminum boat that I am in the process of restoring to be used for a season or two of lake and river fishing before I sell it to upgrade to my next boat. I consider it a project as well as an experience builder as my next one will also probably be a "fixer-upper".

The age of the boat is unknown, however I do know it is a KCraft from Kmart, if anyone can remember how long it's been since you could get a blue light special on a boat. It was last registered in 1993 and has been sitting in a friends backyard for at least 5 years. I have already located and patched most of the holes, with only a couple small leakers remaining that are more difficult to reach. My plan is to paint both the inside and outside, replace the transom/motor mount wood, deck the front from the front seat forward (dog needs a place to ride and provide storage), install basic electronics(running lights, fishfinder, trolling motor, bilge pump), and use the heck out of it.
So my questions to you:
1. The motor mount/transom wood is rotting and needs to be replaced. What is the best type of wood for this application? I also have a piece of thin(1/8"+/-) stainless steel about 24" long by 10" wide to bolt over the wood if that will add strength. I will have an old 15hp sea-king on it with a transom mounted trolling motor.

2. I have stripped the exterior paint to bare aluminum on about 70% of the boat. The remaining 30% is sanded down to the original primer. In order to paint this I know I need etching primer for the bare portion, but can I use the etching over the old primer or should it also be stripped bare?

3. The interior has been sanded smooth, mostly to the old primer. Can I use just a standard primer to prime this b4 painting?

4. The side rail of the boat has no lip on the interior side to run wiring under for features such as nav. lights. I have considered running small diameter PVC or other type of pipe along the floor to feed the wiring through to reach the battery. Is this a feasable solution, or would you recommend another way? I am hoping to prevent having over exposed or hanging wires as well as keep them dry.

Thanks in advance for your brilliance and assistance with my project
~Redneckpunk