It really is a great program. I'm teaching my mom how to use it and she reproduced a great quilt from a pattern she had (so she could play with fabrics) the first time! Including making up her own blocks, as they were not in the palette.
No add-ons necessary unless you want to. I have a couple of the fmq ones, but find that I don't use them very often. You can pretty much get what you need from the internet.