To believe that everyone in heaven is white undermines the relevance of skin-colour (including white); for then we're basically all the same. It seem fairly compatible with being against racism.

The standard disclaimer is that paradise is beyond description, so the (often vague and contradictory) descriptions given are mostly analogy.

There are some hadith which describe the first who enter paradise will bathe in a river and come out with their skin as "white as paper". I think this can be an analogy about sin/darkness is washed away. I don't think there is much mention of people as being "white" as a race as is used today. People were described by their origins, they were Bedouin or Ethiopian or some tribe of Arab. Compare that to some other hadith which say that people in the flames of hell would also be given skin as "white as paper", whenever their skin burns away just so they can re-experience that pain.

By "maidens in paradise" you are probably referring to "houris". There is very little reliable information about what they are supposed to be. Some Victorian era orientalists translated the names to "virgins", which fit in with some popular, but discredited descriptions, that they were supernatural humanoid female-like creatures. Some widely discredited hadith, (but still popular anyway), even say they have transparent flesh so you can see down to the bone marrow. In Shia circles, I've heard a theory that the only description, "they look like scattered pearls", meant that they were simply servants who appeared like balls of light, and relate it to the Persian word for "grapes". Others had theories that "scattered pearls" were description of eyes or teeth who were white because of purity, (regardless of other racial characteristics).