I have an idea to knit myself a patchwork blanket for our camping holidays next year (giving myself plenty of time!). I am a novice knitter but can manage the basics. I am planning to use leftover wool from other projects/other people/charity shops etc so it is unlikely to all be the same thickness of wool. My first question is what size needles do I use for what thickness of wool; is there a general rule of thumb? And my second question is how will I know how many stitches to cast on so that my squares are all the same size?