60x50 is 3000 Sq Ft which is between 1/14th and 1/15th of an acre.
The main thing aeration affects is the amount of fish you want your pond to hold. Is it 100% necessary? No, but it helps.
As far as adding fish, once you see that the water is holding and you have a few feet in there, I'd think it'd be safe to start adding FHM. Just remember, you're using clean water from a hose, and newly added fish (minnows/bait) will need some microscopic critters to eat, if you're not going to feed them. I think the experts will probably say to wait until next spring before adding fish, though.
