Since you're boat will be electric, you can get away with enamel. IF, however, you plan to use decals for the lettering, you will need to spray a clear over the top to protect the decals. I would recommend that you test your clear on a sample of the white to make sure there won't be any issues that could ruin your paint job. With my boats, most will get a coat of white primer, sand it smooth, add a second thinner coat, sand it slightly, add lettering or decals and spray a couple of coats or clear to finish it. The exception to that will be the new Elam hull I'm building. It will get a specific white paint over a tinted primer, neon orange as needed over that, followed by two or three coats of clear over the decals.
As for your hardware, I would install all of it PRIOR to installing the decks. Something else to look at is where the screws are used. Sheet metal and wood screws won't work as the wood isn't strong enough to handle the stress. I would recommend doing one of the following:
1) Install a plywood doubler inside the locations where the hardware will be mounted. For the sponson and rear fin/rudder brackets, you need to have at least 10mm in total thickness and have the doublers cover a larger area than where the brackets will be. Drill the locations for the mounting screws and then install either threaded inserts or blind nuts into the holes
2) Install an aluminum doubler at least 3mm thick inside the transoms where the brackets will be. Drill the holes for the screws and tap threads into the aluminum doublers.