Sole memberships and p.o. box address for Virginia LLC
To answer your questions: yes, Virginia does allow single member LLCs, and no, it does not allow the business address to be a P.O.Box (must be physical address).
The language on the Articles of Organization for this article would be "The address of the limited liability company's principal business office where the records of the limited liability company are to be kept is ....", so it must be a physical location. Same goes for registered office address (the address for service of process).