I used 10,000 BTUs for many years to cool an area quite a bit larger than that, and never had to put it on the "high" setting, so you should be fine.

That should be big enough to get the job done. A small fan in the foyer would help even out the temperatures between the bedroom, and the rest of the apartment.

12,000 BTUs should cool 600 sq ft no problem. You might put a fan in the doorway of the bedroom to improve air flow.

where do you live? (that's probably the most important part)

upstate NY shouldn't be a problem. It won't be freezing cold in your apartment, but it should do the trick. Humidity is usually the enemy

It all depends on how much BTUs your unit is. if it is about 10,000 it should take care of the whole apartment.

http://images.apartmentfinder.com/phototmp/photos_nt/88472/0AB368E4-5D0C-4021-88C8-DBEA4088F05D.gif

I am going to be as specific as I can: the apartment is 601 square feet and the air conditioner is 12,000 BTUs.The wall air conditioner is next to the window in the living room. The air conditioner definitely seems big enough to cool the whole apartment to me... will the cool air reach the bedroom and cool it? Is there any reason why the a/c unit won't cool down the entire apartment? Am I missing something? Please explain........