Hi Nuccia!The hook size varies with the technique. The heart, for instance, produces a very dense fabric because you're working one yarn strand over another. If you used a smaller hook, it would pucker. The designs are altered with number of rows/rounds to all roughly come out to the same size. The yarn used is the same trhoughout.
I'm working on two of these afghans right now & will be posting more details. Is there a square in particular that you'd like me to focus on?
Have you picked which yarn you'll use yet?
I would really appreciate if you could tell us what brand of yarn you used for the original project.
I haven't bougth the yarn yet.
I like very much the colors used in the original project, but it's difficult to find a type of yarn that have all these colors.
Could you write here the type and brand of yarn used for the original afgan and the color codes? It would be useful.