EACH county has it's OWN regulations. The county code section for Fairfax (41-2-7 and 41-7-1) does not apply to other counties. Loudoun and Shenandoah counties, I believe, are a few that don't have the same regulations regarding exotics.
:::NO, caimans (any crocodilia), venemous animals are banned.
:In Fairfax and surrounding counties of Northern VA, all venomous snakes and spiders are banned, ie cobras and tarantulas. Its been like that for awhile (as long as I can remember). Contstrictors are still 100% legal tho.