I have a home tool kit that came in a hard plastic case with fitted spaces for all the tools. It has a basic 3/8 and 1/4 metric/SAE socket set, screwdrivers, pliers, needle-nose, a claw hammer and jewelers screw drivers. I have been surprised over the years how handy it is. I also have a regular hard plastic toolbox that holds everything else, files, wrenches, hacksaw, a mirror, and everything else I have found I needed over the years. BUT, each boat has different needs. I have a new boat now and I am finding the tool kit needs redoing. The tool boxes need to fit and should be picked for their size. Multiple soft bags might be easier to stow.
Electrical depends on your experience.
Power tools can go either 120V AC if you have an inverter, or good quality rechargeable tools. 12v would be preferred so you could fab up a cigarette lighter plug with cord to power them when the batteries go dead. The new lithium tools work well and hold a charge for a long time. A drill is all you really need but lots of other tools can be handy depending on the boat and how much work you plan to do to it.