Is it permissible for a woman to hold her husband's penis with her right hand, and can a man touch his wife's vulva with his right hand?

It is permissible for spouses to enjoy each other in any way, with the exception of anal intercourse or intercourse during menstruation. Therefore, enjoying each other in the manner mentioned in the question is not forbidden, but it is preferable not to use the right hand out of respect for it.