Forrest,
There have been a number of small. electrical boats for many years--Elco, Duffy have been around and I am not aware of any problems. There are many rental fleets as well as private owners. Electric motors on aluminum boats don't seem to be a problem.
There are a number of diesel electric larger boats--submarines, work boats, tugs etc.
With the outboard the leg is to of the water except when running. With our Torqeedo we often took the battery off to charge. we have had that about 8 years and no corrosion, including several year of use in the Florida Keys.
As far as electrical fields, some fish are attracted and some repelled by an electrical field. But Depth finders have been implicated in scaring fish,, others say no problem (ultra sonic)--but there seems to be no issue with trolling motors.
Engine noise with any boat can be an issue, so does any noise on the boat.
It is surprising the number of electric motors designed specifically for electrical inboard use--as well as outboards.