Unfortunately the Xexun website doesn't seem to want to play this morning, but if it's a tracker (as opposed to a navigational device) you need, have a search through the forum, there have been plenty of discussions on this subject in the past.
I can't see the preoduct in detail, but just as an observation, the things you want it to do, would you be better just buying a bigger / better tracker rather than mucking around with one that doesn't do what you need?
As for the 4 satellites, you only need 3 to get a 2D fix. As I assume the police aren't going to be able to do much at 30,000 feet if it's on a 'plane (where the metal body would kill the signal anyway so altitude calcs become irrelevant) 4 should be more than enough, especially if the 4th is the EGNOS / WAAS bird. Also the more satellites, the more maths it has to do, so the battery gets eaten quicker.
There is an argumment that if you want to "play" with it, something like a Garmin 12 off Ebay might be a beter bet?