I live in Arlington (Ballston area). Is it possible to ERE here? Yes, but it depends how much you make, what type of housing you need, and where you want to live. I only ER (40% of salary saved), but could probably get to over 50% if I was willing to give up things like location, going out, car, etc., but I'm not.
Outside the Beltway the cost of housing drops a lot and has a lot of traffic. However, housing inside the Beltway really holds it's value and is usually a better traffic option (depending on where you are going).
Traffic is definitely a consideration here, as it is terrible and completely unpredictable.
I currently rent a basement apartment for $1200 in a very urban area. This is about as cheap as I'm willing to go. Admittedly, it's hard to get much cheaper considering that number includes all utilities and cable/internet, and I refuse to live outside the Beltway.
Alexandria can have ok priced apartments and it's in between Quantico and the Pentagon.
Many neighborhoods have HOA, but I think most of those are either planned neighborhoods (not most of Arlington or Alexandria, but further out it seems to be more common) or townhouse plans.
If you want further clarification just ask.