The patch for Princess Waltz is out, but it did take more than a year before it was released. Demonbane was just released, so it will not be receiving the patch for some time.
As for installing to a flash drive … I have no idea where the game stores its savedata. I tried to move the savedata from my desktop to my laptop so I could play at ACen. I couldn’t find it. So I ended up just using text skip. Also, the game does make some registry changes; so I doubt very much even if you did install to a flash drive that it would work on any computer it hadn’t been installed to.