Creating a multilingual blog platform: advices and experiences welcomed

Hi!

I'm working on a blog platform that will start in french but I'm willing to make it avalaible in other languages in the future.

I've been searching for better solutions but it looks the less headache solution would be to run a different WP installation for each language (with same themes and plugins). Am I right?

If yes, then I would like to have a different subdomain for each language (fr.example.com ; en.example.com ; de.example.com ; ...), each running its own Worpdress installation. However I want my users to have their blogs on the main domain (blog1.example.com, blog2.example.com, ...) regardless of their language.

Is that possible? Is that the way to go? Would you have any recommendations on how (and where) to set up and configure my first french WP instance in order to prevent future problems?

Thank you very much for your help and sorry for my poor english.

Laurent