It seems you have good skill set to build on.
When you are cooking at sea in a monohull you want minimal pace in a gallery so that you can be more stable. You also need a galley harness
to hold you in place. If you like big galleys, I would agree with Len that a multi-hull is a better option.
Marine quality stainless is expensive and there will be a a lot on board. Poorer quality stainless will simply corrode - that is not good. Marine electronics need to survive is a salty environment.
Showering on deck is another option. I have done that often. The showers and head is usually combined. Offshore you really do want a head in which you are not going to get thrown around. I have also spent passages on which I simple washed myself off with a face cloth. You are describing a "navy shower" which is standard fare on boats with a good water supply; they usually have watermakers, on which you cannot depend 100%.
The guns on boats issues has lead to some of the worst discussions on this and other forums. Very little of the rest of the world is in line
with American thinking of self-defense.
Len is telling you to get some serious experience before you follow your dream. For too many people jump in and discover that the life is not for them. It really is not as romantic as the movies
make. Offshore sailing sailing is best described as long periods of tedium punctuated by episodes of terror.
I really would suggest some lessons first. Then charter some boats that have designs similar to what you might like. Go to some boat shows and walk the docks.