Hi Isaac,
I think your 7-channel PCM system is fine. You only need more than 4 channels for pan, tilt, and maybe disabling the OSD display. It should be fine to start with.
On today's R/C systems I have not seen any jitter problems with extending the servo leads. Even on my big 42% Ultimate Biplane, the 6' extensions had no problems.
The best way to increase range for FPV is to use 72MHz for your R/C system and 900MHz for your video link. You may likely run out of battery power on a round trip of 12 miles.
After the summer months I got hit by the MRC bug so it has been quad-mania for me since.

You can see my new fleet [link=http://www.gregcovey.com/multi-rotor.htm]here[/link].
Good luck with your FPV venture! Both FPV and MRC are hot areas of R/C these days and I enjoy the technology fix I get from both.