1. I do not know. Googling didn't turn op much either.
2. No, USB Loader GX has no such option.
3. I do not know.
4. Not really, the hash numbers (or md5 checksums as they are also called) tell you wether the content of a file has changed, because changing the content of a file changes it's md5 checksum. For example, if you copy a file and the md5 checksum of the copy and original do not match, you know that the copy process went wrong. The chances of this happening are quite small.