You can use the same style, picture and template path but you have to maintain 2 setups. You also have to setup an intro page who let the user select wich language he like to use. Thats a hobby coder workaround.
We start to discuss the theme in our boards. Up to 90% like to decide themself wich language they use. We people who speak german only, we have a handful native english members and some who like to switch.
When I search with google and hit a native france board I have to leave because I cant understand what they say. English is in internet the prime language and should be default for international sites but you may have a option to switch to your native language too.
