The major issue I see here is that someone can upload and make you share a copyrighted material. It could cost you lots of money. I wouldn't be surprised if it will be abused...
I use regularly English, German and Romanian. I find it easier to learn using the two extra standard layouts (not the programmer version) and change between them by ALT-SHIFT than pressing ALT-X for every diacritic. The WPM count falls drastically using the ALT key all the time.
Instead of setting up a standard proxy, you set up a standard ssh server, which can act as and/or tunnel to an internal proxy (e.g. by using the ssh -D option to create a SOCKS proxy).