97 Ford Expedition anti theft trouble?

The vehicle starts fine when it's been off for a few hours, however if left off for short periods of time will not start again. Also the anti theft light doesn't even turn on at all. Is this a battery issue or an electrical issue

I think I was ripped off from a local dealership?

I have a 2008 Ford expedition. Last weekend it would turn over but not start. We had the fuel pump replaced. Today, the same thing happened. I checked the voltage on my battery this time, and it was at 10VDC. When I jumped my car, it works fine. Could the 200 dollars to replace my battery, have saved me 1200 for the dealership from replacing my fuel pump? Wouldn't the computer system tell them this?

2007 Ford Expedition vs 2007 Chevy Tahoe vs 2004 Lincoln Navigator?

I wanted to get one of these due for the 4 wheel drive in the winter. I live in Boston, so it gets rough. I wanted to get one of these three. And I don't know which one is better.

I test drove a 2007 Tahoe, and loved it. Although I never drove an Expedition nor Navigator. (although I drive a Lincoln Continental, so I might understand lincolns performance in a navigator).

If anyone has one of these, which one would be better?

Why is the ac in my expedition blowing hot air?

I have 2000 Ford Expedition and recently my ac stopped blowing cold air. It will blow cool air when I first start it, but then goes straight to heat. I've checked the refrigerant and its full. The compressor is also working fine. I changed the relay to see if that would help but no change. I don't know what it could be. Any thoughts?

Also the heater core went out about a month ago. But still had cold air until about a week ago. Don't know if that would be related.