Yep, have to consider ALL of those factors when determining how much land.
If I had to make a checklist it would be:
1. LOCATION - most important. Rural, but with decent access to things prior to SHTF. A good distance off main roads, and away from any key looter target locations.
2. WATER - access to replenishable water (rain water is good too)
3. TEMPERATURE - there's a reason our ancestors feared the winter, pick a place that doesn't get snow and you're golden.
4. NATURAL BARRIERS - tree-lines, bushes, etc. are great for defensive lines and for hiding your location.
5. NON-GRID POWER SOURCE - whether water, wind, solar, etc., at long as one of these is a viable option there.
6. AREA - Make sure you have enough area to grow food, tend livestock, etc., but also that it isn't too much land that you can't patrol/defend it on foot with the people you have there.
7. WAY TO DENY ACCESS - whether felled trees, a taken out bridge, etc., need to have a way to block the road/s leading to your place, to weather the first few months post SHTF (because that will be the most dangerous time)