Re: one of the OP's questions, I've always sorta figured that Betazoid society was historically matriarchal and that, traditionally, the husband takes the wife's name. Obviously there is some personal preference in the matter by the 24th century, just as there is here in the 21st, but I always felt that the "norm" was for the male to take her name.
There is possibly a hint of that in Nemesis where Picard teasingly addresses the recently-married Riker as "Mr. Troi."