US/JP online compatibility & thread for JP Wii owners

[Arnaud]

Two questions for owners of JP version Wii (like me) :

Will I be able to play online with owners of the US version of the same game or it is not compatible ?
Is there any thread to share Wii codes for owners of a japanese Wii ? If I cannot play with US Wii owners, there is little point in sharing codes with them, is there ?

Thanks for your help, I hope this has not been posted before, I couldn’t see it.