Congratulations! I think you will love it.
Regarding fabric, be aware that you don’t have to rough-cut much if you don’t want to. Excess fabric can hang off the edges of the die.
Regarding dies, my advice is to just buy dies for each quilt as you go. You don’t need every die you might use right away. Wait for sales.
My favorite dies are those with odd shapes that would be otherwise difficult to cut — tumbler, hexagons, circles, triangles, etc. I am not a fan of the strip cutters although a lot of people like them. I prefer to use a June Taylor mat to cut strips.