Data Format:  Unity3D (or JSON Hashtable, then change extension from .json to .txt so Unity picks it up as a text asset)
Allow rotation is OK
Everything else at your discretion
Power of 2 output textures are suggested.

Create a folder in your Assets/ directory for your imported sprites.
Copy the TXT and Image file (PNG, TGA, etc) into that folder.
Your paths should look something like:
	Assets/MySprite/MySprite.txt
	Assets/MySprite/MySprite.png

Transparent Unlit - 
	The default shader for all imported sprite sheets.
Opaque Unlit - 
	nontransparent tintable shader great for drawing backgrounds that don't need alpha.  Very efficient.
Vertex Color - 
	Does not have an inspector-tweakable color property.  All colors must be set by altering the colors[] or colors32[] array of a given mesh.  
	Supports both texture alpha and vertex color alpha.