An unimaginative friend of mine playing in my Eberron campaign wants to play a drow ranger (cough Drizzt cough). I don't mind, but I wanted to get an idea of how Drow PCs are typically handled in Eberron. From reading the campaign guide it seems like there are a large variety of different humanoids throughout Eberron even though it is primarily dominated by humans.
This guy's not much of a roleplayer and I don't want to get stuck in a situation where I've got to develop all of this side story that he's not going to utilize so I guess I just need to know if I can "get by" with him being more accepted by the NPCs the party interacts with. I know that as DM I have final control, but I don't want to completely butcher the campaign setting by allowing this...I am a purist in that regard.
The most common population-wise, and most likely background for a ranger are the Vulkoori drow- the drow who worship the scorpion god Vulkoor (Often considered by Khorvarians to be an aspect of the Mockery) - they are tribal and treat scorpions as divine beings, using their chitin as armour and their venom to perform ritual scarification and tattooing on their skin, leaving intricate white designs. They invented a heavy blade designed for throwing, often called the drow long knife, and also use whips (sometimes barbed with scorpion stingers) and boomerangs commonly.
The second most commonly encounter drow culture is the Sulatar. They are a group of Fire-binding Drow who learned the techniques to bind Fire-Elementals from their former Giant overlords millenia ago. They consider themselves always at war with Vulkoori tribes, and commonly use Bronze weaponry, bound with Fire magic.
The rarest Drow Culture are the Umbragen, the Shadow Drow of Xen'drik. These secretive drow are the only Eberronian drow who tend to live underground, and they have embraced a source of power they found in Khyber, granting them great shadow magic power. They're largely secretive and unknown to the world, living near a mostly unexplored region known as the ring of storms.
None of these cultures are particularly fond of outsiders, but are not generally evil, and some of the northern vulkoori tribes do trade regularly with Stormreach. So the player will need a reason they have left their xenophobic brethren.
In terms of something directly useful to your friend, Stormreach is a good place to put your Drow. You can come up with a story about how he was separated from his tribe either forcefully (captured by an expedition, sold as a slave, etc.) or voluntarily, and grew up learning basic social graces.
As far as occupation, there are also tons of opportunities for a Drow Ranger to act as a guide into the interior of the continent. Xen'drik is famous for its Traveller's Curse, a continent-wide magic effect that distorts time and makes like hard for adventuring parties. Natives, however, resist the curse, so your Drow Ranger friend might be in big-time demand.
If you don't want to go that route, the Red Ring is also in Stormreach - a gladiator pit where games go on all the time. Your friend could have been a Bloodbound gladiator and somehow earned his freedom.
There's other stuff. There are whole 3.0 sourcebooks on Stormreach and Xen'drik. Not that your friend will read them, but you'll enjoy them :P.
Overall, drow look enough like elves to get treated like elves in the absence of other information. Whether that's good or bad is largely dependent on the drow's reaction.
In Khorvaire, most people are nationalist rather than racist, so a character is going to garner a lot more suspicion for being a 'darned ferner' than being a black elf. Most of the time in any case, the average human villager only ever sees an elf when the circus comes to town, so they're hardly likely to register drow as being any different.
I'd disagree on the average person not seeing elves that often - most villages of more than a couple families likely have a couple of Elves or Dwarves or Gnomes, or at least see them regularly in trade - even more so if there is a nearby trade route or dragonmarked house business.
In most parts of Khorvaire, the human population outnumbers the elven population (or for that matter, any non-human population) by about 10 to 1, and most of those elves will be concentrated in large urban areas (making the ratio closer to 500 or 1000 to 1 in smaller towns and considerably more skewed in villages and farming communities). Isolated communities are not generally known for being cosmopolitan, as well: even in nations where humans don't outnumber all other races combined by 2:1 or more, individual communities are more likely to be racially homogenous than not. Elves are not known for their mercantile bent, and Deneith-sponsored Valenar mercenaries tend to be kept away from anything that might tempt them to supplement their contracts with local plunder, so that leaves Phiarlan- and Thuranni-sponsored entertainers as the primary elven commercial traffic outside of towns and cities: i.e., when the circus comes to town 
So, unless the campaign sticks to heavily populated areas consistently, most of the people they encounter will not be able to point at a drow and definitively declare 'that's one odd elf' based solely on skin tone (or even dress or behavior). They will know that the character "ain't from 'round these here parts" and react according to their level of nationalistic (or even more local) insularity rather than simple xenophobia (and their first instinct will be to assume that the character has something to do with the circus, if the drow continues to dress in a manner consistent with their tribal origins).
I don't know too much about Drow in Eberron and I was wondering, would you just use all the FR rules for drow PCs but with Elven language replaced with Giant?
Certainly. Of course, the similarities end with the crunch aspect.