Showing affection in the nude
As long as they're being discreet and not deliberately trying to offend others, anything they want to do is okay by me. It's not like any of us don't already know about basic biology, and doing it in the outdoors is always enjoyable! Once again, as long as they'r discreet.
Do you think it's wrong to kiss/hug/cuddle your spouse/partner/friend/relative while on a nude beach?
considering all the other things I have seen on the nude beach here this is the least of anyone's worries. The consideration for public affection is always this. Is your need to show it or receive it greater than the potential disruption of social or group norms? If not then there is no need to worry. If so, whose norms, for what end? If it is a natural part of the way two people interact on a daily, then stopping it for some propriety "issue" seems heavy and harmful. However, men especially use "social" hugs in lots of settings beaches included to force themselves into the space of a woman or young man (older too sometimes), and because of that, I don't think group hug exchanges or kissing everyone and cuddle puddles are a good idea.
I think there is nothing wrong with being affectioned or kiss/hug someone on a nude beach... I always though nudists were tolerant people, so this should also apply. So in my opinion be free in your feelings, but never go too far on a nude beach (depending on the kind of beach you are visiting ;-) in order to shock other guests.