I've done a fair bit of pattern testing, as well as piecing probably 40-50 quilts from patterns, roughly 10 of those being queen or larger.. All of the above are valuable items to consider. The other thing I'd like to throw in - please use either #'s or Letters to identify the different fabrics. (7 fabrics numbered 1-7 or lettered A-G, etc. It's frustrating to me to see a pattern made from a specific line using the 'name' of that fabric in the instructions instead of a generic identifier! That forces me to either 'name' my fabrics on a chart so they match the pattern, or go thru and 'edit' the pattern to capture #'s.
IF you're going to have PDF downloads available, and if you are including color photographs of fabrics, top, etc.; be sure you print your pattern in grayscale so you can see how much difference/variation there will be as not everyone has a color printer at their disposal! BUT do show several options using tone, hue, prints, etc.
Good Luck and will be interested to see what you come up with!