"Factory farm" is just a term used by opponents of large-scale animal agriculture to refer to Concentrated Animal Feeding Operations or CAFO's. It's difficult to say what the average is, since it varies so much by the type of livestock produced there. An average poultry CAFO might be 300,000 birds, while an average cattle CAFO might be much fewer at 5,000 head.
No. The biggest type of bovine is typically the beef cow. There are beef cows around that weight more than a big dairy cow, and that can be upwards of 2000 lbs or more.
Depends how big is your garden ;)
Nothing wrong with that. Dairy cows are slaughtered for beef as culls anyway, so it's no big deal if you slaughter a dairy cow and turn her into ground beef.
A cow. Or, if you want to go into specifics, a dairy cow.
It gives more milk than what it would normally produce for its calf. That's what constitutes a cow for being a dairy cow.
Dairy
The dairy cow.
That all depends on the breed. Are you asking about a dairy cow or a beef cow, and what breed of dairy or beef cow?
Dairy cattle like Holsteins, Brown Swiss and Jerseys.
A dairy cow would die a matter of a few weeks before she even gets to the point where she is deemed "feral." I would see a beef cow becoming feral, yes, but not a dairy cow.
A farm
There's not really an answer... You just call it a cow...