Based on my experiences in South Florida, if it was me, I'd go full insulation, preferably closed cell foam insulation. Much more efficient & adds rigidity to the structure. Mice love to nest in that fiberglass stuff. Also A/C for sure. Say from April/ May through to October it is hot & muggy. April through to June it's rainy season. June through November is hurricane season which could mean any number of tropical storms. All of which means moisture.
For water lines, I would highly recommend copper. I install kitchens in multi million dollar homes. They all use copper. That plastic tubing may be cheaper but will eventually burst inside a wall & cause water damage.
