Can you park in this lot to get on the bus? Is there non-Safeway parking here?

Always look for a park-and-ride sign in an area where you desire to park and get on a bus if you contact Cobb Community Transit they would be able to inform you as to where the closest park and ride is

I can't speak to how official the status is, but people do this all the time, parking for the bus or working nearby.

Actually you need to park on the street or in the nearest 'park and ride'. Christ Church near 10th is an official parking lot. There may be others, also. If you are picking up or dropping off, Safeway doesn't mind, but people going to work or for a long ride should not park there. No room for Safeways customers. That would be a very inconsiderate choice.