So have the files been converted? If so, try editing them before you convert the files, sometimes converting them I've noticed gives some unwanted side effects.
Use MAS editor, find the files you want to edit right click them, extract, open in Photoshop/other photo editing software, edit what you need to, save. Then import them back into the mas file, overwrite and then save. Job done.
Obviously, your version of Photoshop can not handle dds-files. But just look for the dds plugin in the internet, it is just a small file and easily installed.