Can I be charged with drunk in public or an an open container for drinking with friends on my deck or my front porch?

Yes. Police in Fairfax County will usually be reasonable about what happens in your own house or on your own property.  However, noise and other types of drunken activity can result in arrest, and so it is a good idea to be quiet and polite if they come to visit.  

Don't let Police into your house by consent unless they have a warrant, and don't come outside and talk to them if you have been drinking.  If you are inside your house, it is very hard for the poice to arrst you unless they obtain a warrant first.