1) Don't know if French will be in the final game, but you seem pretty good in English.
2) Didn't had a problem with it, but ok, why not. Might be helpful if the final game.
3) Performance is currently bad, because of unoptimized AI, not because of graphical fidelity. But anyway, you should consider to upgrade your PC later, when the game is final. If optimized, the requirements won't be to harsh and a medium spec'd PC should handle it just fine.
4) Finaly game will be available via steam.
5) Launcher slow? It has to download the game once. After that it should just start the game within seconds. Download speed depends mostly on your internet connection.
6) It was already stated, that there won't be any more updates to the beta. Launcher updated automatically to new version, when update was available.