Why are some non-towered airports charted with an empty circle?
Your first stop for questions like this should be the FAA Aeronautical Chart User's Guide. In the VFR Sectional &amp; TAC section it says:


  Runway patterns will be depicted at airports with at least one hard surfaced runway 1500´ or greater in length.


If you look up the details for 62C in the Chart Supplement or whatever other source you like, you can see it has two grass runways, i.e. no hard surfaced runways.

As for the hash marks, they do mean that fuel is available.