Law enforcement will just go to the carriers who have your rough location data regardless of your GPS settings. They probably aren't keeping detailed tracklogs like Google today but I'm sure some fat government contracts can fix that.
Yes, but that gives them tower connectivity only. Which is very, very general in terms of location unless you triangulate the location in real-time. And even then, you have to be connected to at least 3 towers at once for that to be accurate, which to my knowledge is not how phones operate. So they will only get the very rough location based on which tower you were connected to and when. In any modestly populated area that becomes effectively worthless in both practicality and the courtroom. In a city like NYC, that would literally result in a dragnet of tens of thousands for each of the major service providers. Even a bad attorney could get that thrown out immediately.
I wouldn't trust that GPS is actually off for the baseband processor when you set it off. This is key for the real time location tracking by phone number.
