I have coded something in the neigbourhood of what you want. What you can do is tell what sets you have and it dowload parts information so you can if you can build the MOC you like with the parts you have, and then get a list of parts you need to buy.
The Notes part isn't that big (right now) just a comment, but that can changed easy. It also downloads the current value (this is why I wrote the software, our insurance company whanted to know the value)
Can this be something?
/Martin