Batch MD5 Hash Changer

No, there is no type restriction. It works on the bytes and never looks at what is inside, so documents, archives and installers go through the same way, and both the extension and the file type are kept exactly as they were.

No. What you save is a separate new file whose name carries a (new) prefix, so it will not be mixed up with the original sitting beside it; the original stays where it is, unchanged.

No. The same original always produces the same new value; if you want yet another one, load the file you saved last time back in and process it once more.