in terms of drag the maximum gliding distance when is obtained ?

Answer 1

when you start higher?

I don't understand the question, but before reposting, you might want to look at:
http://en.wikipedia.org/wiki/Glide_ratio
http://en.wikipedia.org/wiki/Lift-to-drag_ratio

And a truly superb book on this and other elements of flight is:
The Simple Science of Flight: From Insects to Jumbo Jets
by Henk Tennekes