Please give me some good info about how to propperly ground a rooftop antenna mast for lightning protesting. Here are a few specific questions I've been thinking about.

1) I assume I should use either #4 or #6 solid copper wire and copper clamps.

2) Can I run the grounding wire to a copper water pipe in the attic? It's nearby, but I'm concerned about electrifying my entire water system. Is this unsafe? My house is served by a private well, the only source of earth ground to the water pipe system is the bonding of this system to the ground rod(s) installed by the electrical utility at the point the electrical feed enters my house.
This wire is #4.

3) If I can not use the copper water pipe, and have to run the wire outside the house to the gound, can I use a burried copper propane line as the earth ground? It is burried for at least 30 feet, and seems like it would be an excellent ground. It leads to an underground metal propane tank that I know has its own grounding electrodes. Any chance of sparks/explosions here?

4) If I can not use the water pipe or the gas pipe, can I use the same grounding electrode the utility is using? THis will require about 50 feet longer ground wire. In this case, can I run the wire through my basement or must it be completely outside the house to be safe?

5) Lastly, I suppose I could install a new ground rod, but this will be very difficult to sink 8 feet into the rocky ground.