Pffft. All of the angels mentioned by name were dudes and the concept of heavenly messengers almost certainly predates the writing of the Torah. Adam and Eve weren't born. They were naked because God wanted them naked. In the earliest biblical mention of an angel, Satan was naked too, unless you think serpents wear robes.<quoted text>
Most of the time it just says angels. No mention of gender.
I doubt we will be naked in heaven. All mention of angels or Christ always indicates robes.
Adam and Eve were naked for the same reason babies are born naked.