I personally don't know how to switch between languages, do you mean on your keyboard or on
Which file do you receive? Are they doc files? If so OpenOffice should handle them properly,
there are a lot of useful office suites on Linux, you should try them, they should all be
available under entropy, the Sabayon package management system.
My favourites are OpenOffice and Lyx (but this is for LaTeX).
As for dictionary software there are some on Linux, but I don't know them very well,
I know about stardict but I never really used these softwares, maybe someone more
informed than I am will help you on it