Ultra Lightweight 2m Yagi Beam Homebrew Plan

[Steve]

I have a few questions, I'm guessing Lightspeed will be answering.

Is this primarily a "line of sight" system, and therefore of little use unless you live on a tall hill or want to talk to a satellite ?

How much is reception improved over the standard "rubber duck" type ?

Where exactly do the wires from the coax have to join the driven element ? How critical is it ? How long should the "un-coaxed" parts of the feeder cable be ?

How much improvement will extra director elements give ? And what is the spacing for them ? Given room for a loooonnnggg version, an accurate alignment method and a hilltop location, what number of elements will give a useful gain before the law of diminishing returns kicks in ?

Does the element support have to be metallic ? The length is specified to 1/10th m/m which suggests it plays an active part, but I don't know how.

How long can the coax between my Baofeng and the Yagi be ?

If I decided to build one for a frequency of my choosing, for a more private link, does anyone have the formulae to calculate the sizes ?

Ta.