It isn't intended/necessary to download all the image sets (I'll see about rewording some of the page/dl instructions, sorry if it was unclear or felt too necessary - a lot of them are niche packs for certain content); there's also the in-game downloader which should hopefully be a bit smoother.
There's difficulty options in the game settings if you'd like to adjust the odds (and results can be forced using the dev menu (f2) if you'd like to explore them). The long missions where you get a character to transform after accepting a contract are long to give you time to carry out the transformation - you should be able to turn them in when the transformation is complete.