You can do whatever you wish.
My suggestion would be for you to do a block or two as a test, to ensure you are happy with the look you will get without using an assortment of fabrics.
Quantities would vary ... how wide the strips are, how many logs on each block.
If you have a pattern, it'll tell you how much of fabric A, B, C, etc. and you could add them together to know what you need.
Otherwise, when doing your sample test blocks, you could keep track as to how much fabric you use and calculate your needs based on the number of blocks you will be using.
What is Queen size to you ... will be a different size to someone else. ]
Eg. many say 110" square is a KIng yet that's the size I like for my antique double bed!