Wow, lots of questions...

Windex is to remove the excess glow fuel from the plane ( and yourself! ). It "cuts" the stuff in the glow fuel just fine w/o damaging your plane.

The hold down, is to prevent the plane getting away from you when you start it.

Some fields have these already installed so you do not need your own.

-- Consider joining a club and getting training.

Instead of trying to type out long answers look here for some very complete guides to getting started.

[link=http://www.dc-rc.org/bobs%20guides.htm]CLICK ME FOR RC GUIDES[/link]