How do you change block sizes?
 

I saw a site that had a conversation table that you plug in the size of square you want and the number of fabrics and it would give you how to cut and amount of material needed. Lost it :( Does anyone have a site they use?

The simplest way is to use a square ruler the size you want your block to be and draw it out. Add 1/2 inch seams to all the squares and 3/8 inch seams for all the half square triangles.

Try http://www.victorianaquiltdesigns.com
They will send you numerous charts which are listed on the home page. Perhaps the "Quilty Formulas" would work for what you want.
Good luck.