Well
UnknownBava already answered this and if I recall correctly, the swimsuits were the kind of school swimsuit, don't remember exactly where I saw the picture, but either way yes, you need cheat engine for that... Or not, just play on easy let them all get grabbed and don't save them, let them all get killed, revive them with as many "miss" possible to have them back on foot but on low health and that's it, doesn't really changes anything since it's still the normal costume, so they'll just show naked if you heal them or get grabbed by enemies as normal, honestly not worth the effort either way, probably best to wait for the nude mod to be updated with newest build.
On the signatures, DM me so we keep the thread focused on the topic.