Relax..... enjoy this amazing time with your child. Take this opportunity to use simple, age-appropriate words to label what he asks about. He's two, he'll move on fast to something else. If you're really, really concerned about being naked with him, use lots of bubbles! I recommend the Avon Sensitive Skin bubble bath..... you can sit in it for along time and you won't be all itchy... more importnantly, neither will your son. I think now is a good time to start talking to him about appropriate and inappropriate touching... in short, simple phrases - remember, he's two - he needs information in small pieces with simple language. Also, with a positive tone - you don't want to scare him. A good way is to say that the parts of the body that are covered bu swim suits are private parts and he shouldn't let anyone else touch those parts unless Mommy says it's okay. Simple. As he gets older, you can talk more. Remember to include that if Mommy's with him and the doctor needs to touch him, that's okay... sometimes parents get so restrictive with their language and their fears, they forget about the safe times and places.
Really, the best advice I can give is just to relax and enjoy these special moments. Some of my favorite memories of my little guy and gal were in the bathtub - we had some of the greatest conversations, some of the best learning experiences - for both of us, and some of the most calming, relaxing, rejuvenating moments during a sometimes sleep-deprived, working-full-time existence.
Relax, enjoy your sweet-smelling little miracle and don't rush into too much information too soon.... relax!