First things first: download
RECUVA. Formatting will only wipe the boot record, and reinstalling will take up a block on the disk that might well miss your FF7 data. Using RECUVA might let you access and recover data that's still on the physical drive, as only low-level formatting actually 'wipes' data.
Now:
1. PC EFI is not a bootloader, as I recall - but I don't know a lot about it. I believe it's just a means of patching an OS X kernel so that it can boot on 'general' x86 machines with the aid of, say, GRUB (I've never followed hackintosh stuff
at all, though). You needed to apply it, IIRC, to the OS X hfs partition only, and then install GRUB as a bootloader. There's your problem. Applying EFI to your NTFS partition might cause a LOT of issues, or might do nothing at all. Looks like the former...
2. ...That's about the limit of my understanding of EFI, and I'd put good money on the next poster coming in to prove me completely wrong....
3. It is. It's very easy to render a machine unbootable this way. Also, gain a copy of FreeDOS that you can use as a LiveCD. If you install a bootloader to the MBR, you can then use FDISK to repair it. Saved my ass countless times.
4. Use RECUVA as soon as possible. The longer you leave it, the greater the chance the 'defunct' data will be overwritten!
TRIVIA TIME:
Reformatting doesn't actually wipe out data. It just wipes and rebuilds the file table. You can think of a partition like a book. Rather than going through every page to find the info you need, you have a 'contents' page and an index that lets you quickly locate data. This contents page is like your file table. Reformatting rewrites the contents page, but doesn't change the rest of the book.
Reformatting, then, doesn't actually wipe data. The exception is 'low level formatting', which actively overwrites all parts of the disk with zeroes. However, if a particle has been at "one" for a long time, it will still have a 'trace' in its magnetic field - it won't have the exact same response as a 'natural' zero particle. It's therefore possible to take an "analogue" read of the disk, by changing the tolerance of the disk heads. This method will produce 'likely' sector images, which probably represent the disk sections prior to reformatting. These can then be combined and recombined, to create a likely pre-format disk image. This image can be searched for "sensitive" data: credit card info, bank details, or evidence of criminal activity. Thus, neither deleting, formatting or a single low-level reformat action can securely wipe data.
You can get around this another way, by using a 'data shredder', that repeatedly writes and overwrites with ones and zeros, in varying patterns. This can fully 'clean' the disk.
The truly paranoid, of course, simply keep their 'sensitive activities' to some secure flash-drive-booting linux distro, and use a proper proxy service for online activity, though government and law enforcement can often coerce proxy providers into handing over their (extant) records. And for good reason, too.
