Regarding the file systems:
Since FAT is indeed the easier one of this couple, finding full specs on the net is not much of a challenge (check out here for example). NTFS on the other hand is more wicked, but still doable. I'd recommend to start reading up about it from http://www.ntfs.com and then head to http://www.linux-ntfs.org/ for more detailed documentation.
Oh, and a small tip that might hopefully help you out - for direct disk access when playing around with the specs, i really recommend WinHEX. A superb tool for data recovery or any random browsings around the disk (did some file recovery by hand with it once, when my freaky pc thrashed all the partitions on a disk so that no file recovery software did its job decently :shock:. It was a success )

Aye, and something about the api declarations - another way would be to search the header files from windows sdk. Dunno if that would be faster, but it's an option