Congrats on your new purchase. I've had my 6600 for a year and a half and just love it. I took the classes, and am glad I did. You'll learn to use all the feet for your machine... or at least see what they can do. I chose to work with my machine for a month or two, then go in for a class. This way, I could get comfortable with it, and wasn't overwhelmed with all the information. I've found the owners manual very helpful and make notes right on the pages.
I agree the previous poster, wait to get the other bobbin case until you've used your machine for fmq. I do extensive fmq quite well with the original case. Enjoy your machine. You're going to love it!