Regarding RG-6 cabling, you are considering Quad Shielded coax. The Quad shielding simply means there are two foil shields and two braided aluminum shields (usually). Now there is some debate regarding the usefullness of this. Personally I think that the Quad shielding is overkill, however, it is recommend by lots of sales folks and I get asked to install it by homeowners who have bought into this program. More commonly available will be Dual Shield which has a foil shield and a braided aluminum shield. Either cable will do fine for you, and if you are really concerned I would check to see what frequency the cable has been 'swept' to. Older cables (and splitters) were not designed for the higher frequencies being used in cable systems today. Make sure you components are all capable of operating to at least 1000 MHz or 1 GHz.
I sell RG6 quad shield for something like 16 cents a foot, and dual shield for 9 cents a foot just for a price comparison. The type you described is commonly called figure eight cable and is designed for either the aerial drop to the house from the pole (with the ground wire as a support strand) or from the satelite receiver to the dish where the ground wire provides dish grounding.
You should use good quality connectors, if I had a dollar for every twist on "F" fitting that I had to cut off and replace to clean up a signal.....well I could pay someone to write this for me. Use a good crimp on connector at each point, and a female 'barrel' fitting (bulkhead fitting) on the wall plate.
As for distances from electrical sources, the farther the better. Will 6" away from a fuse box cause you problems? My guess is probably not if the box is metal and you only run this for a limited distance. Were it me (and it often is) I would place your terminations in the utility room in a metal enclosure (available from Leviton, OnQ, Ortronics, and a number of home networking companies) and extend a metallic conduit from the box into the attic or crawl space until you are past the electrical sources. Of course, ground the box properly and ground the devices as well (splitters, ampliers, etc).
Good Luck It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com