I've always preferred natural fabrics so most of my clothing is cotton or wool. Long underwear and socks as well as other technical clothing is generally synthetic. Day-to-day living on the dock is pretty much the same as ashore.
Dinghy runs usually mean some spray so I am more careful about fabric choices in the
dinghy. Still, I haven't had any issues with cotton t-shirts -- if it's going to be that wet I wear my foul weather jacket at least anyway. I don't like having a wet butt regardless of the material type so I slow down rather than get wet.
Shoes are the biggest clothing-related storage issue for me, and dress shoes have ended up in the truck. I have a pair of Sperry Topsiders "dress" boat shoes that I can wear even with a suit, but real dress shoes are sometimes necessary for me.
Oh - I use a regular clothes iron plugged into shorepower or I run the generator.
I keep half my suits aboard and the other half in a utility trailer I use for storage. When a suit goes to the dry cleaners I rotate another one from trailer to boat and the clean suit goes in the trailer.
I wouldn't buy all new clothes (unless your looking for an excuse) until you get some experience living aboard and determine what works for you.