You can pretty much
anchor anywhere you want as long as there is enough room between your boat and land, docks, or other fixed objects for boats to pass by you, and the depth is sufficient for anchoring. For example, I sail out of Back Creek in Annapolis and boats heading out to the Bay or back in from the Bay pretty much have to manuever around any anchored boats. During the weeks prior to the U.S. Sailboat show, Back Creek presents quite an obstacle course due to all the anchored boats. You do have to survey the area in which you are thinking about anchoring for other boats already there. Boats swing while anchoring as the wind shifts and the rule is that if boats swing together (hit each other) the fault lies with the vessel that anchored later.
There are some restricted areas. A good set of
charts will indicate restricted areas and prohibited anchorages. Anchoring is not allowed in shipping channels.
Channel 16 is the emergency channel and is monitored by the U.S. Coast Guard. It is also used as a hailing channel by boats and most marinas. It is not supposed to be used for requesting
radio checks, but folks still do it. The USCG will cut in on any transmission that they believe is unauthorized. Channel 9 is recommended as a hailing channel and for
radio checks. When you hail another vessel or a marina on 16, and they respond, you will be directed to another channel, such as 68 or 72. On those channels you can converse to your heart's content.
In my experience, you can generally get cell phone coverage while out on the Bay.
I am not aware of any web sites that provide such information, but it seems reasonable that there may be some. You could do a Google search. There may also be some basic publications that provide such information. For example, I have a book called "Cruising the Chesapeake" by William Shellenberger that provides much information on anchorages and marinas for the entire Chesapeake Bay. It's more like a Zagat's or Consumer Reports, rating places to dock or
anchor mostly depending on amenties, activities, and scenic views.