You would need to use at least RG11 cable or maybe even .500 (half inch), which really depends on the signal level that tge cable company provides at the tap you'd be connected to. It is hard to advise over the Net on this, and the cable company's cooperation will be crucial both in terms of finding out the cable specs and calculating the signal loss budget. Of course, you need their permission to tap which is assumed here.
Make sure you use direct-buried type cable for the outside run and transition in into indoor type (or termiante) less than 50ft from the building entrance.
I don't think coax connections land themselves very well to the redundancy setup you are planning with multiple cables. I have never seen it done (though I have not worked for a TV station where this kind of redundancy would be critical). As far as conductors are concerned, you can only have one core conductor (hence CO-AXIAL cable) with this application. Twinax cables are largely obsolete now and have been used for entirely different application in the past anyways.
Good luck with your project!
Dmitri Abaimov, RCDD