Hello and Welcome to the board
to answer your questions :
1) any 100% cotton will do
2) No the blocks do not all have to have all the same fabric - you can make them scrappy ( means they are all different)
3)White on White will work or solid white -anything that reads a white ( so your fat quarters will work)
Unless of course you want to go shopping and we are your excuse
Just have fun- we are a fun group and easy to get along with
