FOIA 101
Virginia’s FOIA says only this about making a request for records: “A request for public records shall identify the requested records with reasonable specificity. The request need not make reference to this chapter[.]”
There is no requirement that the request be in writing. A request for records is therefore valid whether you ask for them orally (in person, over the phone) or in writing (letter, e-mail).
It’s generally a good idea to put the request in writing, just so there’s a record both sides can go back to for clarification. Sometimes the government agency may ask that the request be made on a particular form. That’s OK, so long as the government doesn’t deny a request just because the form wasn’t filled out.
A request can be as narrow or as broad as the requester wants, so long as the records asked for are described with reasonable specificity. There’s no requirement that a request be narrowed to a particular topic, date, person, etc.
Practically speaking, however, it may be in everyone’s best interest to hone the request: it will take less time for the government to get the records, and it will cost less for the requester to receive them.