If I purchase a mobo and chip here, would it be possible for the bios to get flashed in store (by a professional) before I leave? Your fairfax store is quite a hike from my house...

They would most likely charge for their services however it's not too difficult nowadays to flash, especially if your using the bigger named boards

They will charge to do so, and it's very unlikely they would do it before you leave. They told me 5 business days.

They have a services department in the store. You would most likely have to pay and sign their documents before services can be rendered. You can call them before hand and ask for their services department.