About Twips and things:
You can set the form's ScaleMode property to something other than Twips (like Pixels). The Width and Height will always be in Twips but the ScaleWidth and ScaleHeight will be whatever you selected.

About wave headers:
I don't think you can add a description, unless you create a new header format. Don't do that, there are too many around.
For more information, download a document about the BMP format from http://www.wotsit.org.

U 1337 h4x0r