[TowerTalk] 80m 1/4wave vertical construction

[Dave N0RQ]

I am hoping to build an 80 meter 1/4 wave vertical, but have several practical questions.

Size of aluminum tubing?  I don't want to waste $ and buy too big, but obviously
don't want it too small either.  http://www.texastowers.com/aluminum.htm
shows what TT sells (and thankfully they are local to me).  I plan to get the 12'
lengths (unless that is a bad idea for some reason).  Do I start with 1.75" and step
down ending up with 1.25" on top?  Bigger/smaller?

What about a guesstimate on the length, using tubing like this?  If a wire dipole leg
would be 61.25' (468 / 3.82MHz / 2), what would be a good starting length for tubing?

Also need an idea on making some sort of attachment point a little over halfway up
to attach some dacron "guys" for support.  Simple smallish eye-bolts?
Should I be concerned about dacron getting wet and affecting SWR/performance?

And what is the best way to attach the bottom of the antenna to a 4x4 post, 
maintaining insulating properties from the post but yet very strong.  Perhaps
grey PVC over the aluminum and some sort of bracket?  I'm having problems
visualizing it...

Dave N0RQ