For what you've mentioned, I think you'll need a significant description of what your setting's grey elves are like, in most regards.
For me, it generally depends on the homebrew, and on how different the race is from the standard ones in the Player's Handbook.
If it's a race based on a core one (like variant elves, dwarves, etc.) or a core monster race (variant orcs, goblins, etc.), I'll tend to give just a brief mention of how they're different, primarily in terms of appearance (including preferred clothing, combat gear, and architecture), basic lifestyle, and personality or motivation. For instance, noting if they're very honorable, or tricky, or honest, or competitive, or aggressive, or patient, etc. I'll mention what alignment tendencies they have, and what basic sort of religion they have (or what deities/spirits/forces they venerate). The types of location they live in, or the specific areas if important enough, are also mentioned.
For ones that are significantly different, I'll give them a few paragraphs of description (mind you, this is in printed or e-mailed notes; in speech I'd just mention a few key points, and give the players a handout with the relevant notes if they're interested).
If the race is not even based on a core race, I'll go into much greater depth; at least equivalent to what the Player's Handbook gives on each main race, though not likely the same format.
For more specific reference, take a look at the racial entries in my Rhunaria and Aurelia homebrew pages. Rhunaria is on my Geocities homepage, linked in my signature; the entries on Humans, Dark Elves, and Dwarves are probably best indicative of the extent to which I detail fairly different variants, whereas Orcs have a slightly short description since they're much like Monster Manual orcs. Rhunarian Dark Elves have an expanded entry, the only race I've completed that for, as of yet. My Aurelia content is in a thread on EN World, also linked in my sig, and I have a few races scattered in that thread; Humans have the longest, while Aeragi probably have the shortest description there. Still more detailed than the Rhunaria racial descriptions, though (except Rhunarian Dark Elves).
I also have even-shorter racial descriptions, in the EN World thread about creating new races and judging the right ECLs/LAs for them. I don't have a link right now, but I bumped the thread some weeks ago (maybe a month or so?), so the thread should be only a few pages back on the House Rules forum (thread was started by Xereq, I just can't remember the exact name of the thread itself; started with "Races: Creation" though). I still have to finish working on a bit of background description for a few of those races, though (been busy elsewise).
