The best place to mount antennas on a pickup truck, it the left rear stake pocket mount. Not all trucks have them, however. Of course, you have to do a good job of bonding the bed to the frame.
There are several ways to get into the cabin of an F150. If it is an automatic, the best place is the clutch grommet that isn't used. On some models there is an extra 'tit' on the main wiring harness similar to the one all Toyotas have. It is NOT big enough to pass a fuse holder through unfortunately.
Under the carpet in the rear corners are grommets made to pass through trailer wiring, etc.
On the install I did, the radio was mounted under the front passenger seat, and the head of the 7000 on a bracket screwed to the center console. The controls were easy to use by simply laying your arm on top of the console.
If you're has a navi, you might want to look at remoting the front panel onto the navi. I have info on the device on my web page under Neat Gadgets.