But here's a few questions:
-IF you were doing an OA style setting...would you allow one of your players to play a PC that by their own description was caucasian (ala Last Samurai) or vice versa with a primarily european styled setting?
Yes, though reactions to them would depend on the locale in question. In a major city, noone would likely raise an eyebrow. In a small town, they would likely get more shifty looks(much as any non-human might).
IMO, if a town/city/nation is racially tolerant, that 9/10 elves, dwarves and the various "other" races will get equitable treatment to the humans, people aren't going to think twice about a human with a slightly variant skin-tone and strange features.
In the specific case that someone wants to play a sexy bald black man on a horse, I'll whip up a very basic "home area" from which people of that description typically hail.
I once went to far as to make a small campaign setting where (all) dwarves were black, simply to force players out of the "dwarves must be irish/scottish!" idea.
-How often do your homesettings include all ethnicities of humans that exist in real life; do you make room to include specific lands that these people hail from?
It's a matter of necessity, if I find it necessary, I'll do it.
-Do your elves and dwarves, etc include as much variety within one another as humans? Or are all your dwarves scotts?
Sometimes, yes. Elves are a hard case because the game already outlines several "racial variants" of elves, but not so much of dwarves. So generally play by that and allow elves to be diverse, but still each is an exclusive group, while dwarves are a more inclusive culture, but have much more limited racial variants.
-In your experience, do you (or your players) when playing Humans at least, tend to play characters who are of their own ethnicity, or does it depend on the setting?
Personally, as a mild-mannered middle class white man, enjoy playing black and arab characters. it's a fun exercise in breaking my own molds.
honestly, most of my players, and most of the people i've played with, dont play humans at all. So I don't think I have a good bearing there.
"You almost never see black people in D&D or FRPG art-its like one in a million. If you or me were to just magically show up in a fantasy setting, 9/10 times people would be like 'Where did you come?' "-friend of mine to me once
I would wager that there are some good economic reasons for this, but in my experience, recent gaming books have been much more diverse.
It makes me feel good to see the PF paladin.
I hate pathfinder's art, but it's a good all around "I can represent anyone" picture.
At the same time, you also have to consider that while there are a wide array of humans, there are also a wide array of tiflings, gnomes, elves, dragonborn, dwarves, and many others. Aside from humans, this is a LOT of races/ethnicities to represent in a limited RP book.
I'll also bring up the oldschool Queen of The Spiders; on the cover of which the drow are black. I thought it was kind of hot ;D.
http://tsr.bothgunsblazing.com/dd1/gdq1-7.jpg
On a random side note, how have the drow changed? I know at one point they were night black, then black (ethnically; but not for long), then blue, and now in more recent incarnations this kind of purple color.
The drow are mostly dark greys, to dark blues and dark purples. I think they've strayed away from making them ethnically black to avoid the accusation that they were portraying black people as evil.
Personally, with elves, I consider that they 'tan' backwards to humans, as elves in forests seem to always be light while Drow are dark. I get that this is more a representation of "good" and "evil", but I think it makes it fun to consider that an elf who spends all day sun-tanning could end up white as a sheet, while an elf who spends all day in full-plane and dungeon crawling would darken.