RE: How much land?
I'm with wildpigs remarks. Comes down to what you can afford, the more the better to try and manage a deer heard. Me, I was able to find 92 acres in the Southern Tier of NY and I pretty much hunt it myself with 7 hunting locations within it.
Also, be careful about buying land with others. What sounds like a great idea now, will be a nightmare later. JIMO.
Good Luck!