Advice for 1 person and 1 cat in an apartment?

I should explain that I live at home and will move out to a 538 square apartment soon. I will live there alone, so I would like to get some company and get a cat. I grew up with cats so that's a logical choice. I just have a few questions. 1: is 538 square feet sufficient for one person and one cat? 2: Are balconies safe for cats to enjoy outside stimulation? 3: What can I do to further enrich the life and environment of an inside cat, since it will almost certainly not roam outside. 4: Since I will be living alone I won't have anyone to look after the cat while I'm gone. I'm only away 2 and a half days but will it be alright on its own? What can I do to make sure the cat is okay while I'm away, and for how long should I be away tops?