Great engine, great tools, at first (congratulations are never too much especially when you come for help

I have some problems when it comes to get 3dsmax communicating with Irredit.
Look, I just modeled this nice tree (well, ok, it is not perfect but it is a test


But when I export it, it won't work, giving me some wierd result (and the few times i can have my mesh properly my texturing is not imported). I tried with . 3ds .x and .obj but always something wrong.

Maybe it is the way I made it under MAX (though nothing so fancy, UVW mapping for leaves and that's all, the leaves are cubes). Maybe it's the way I didn't do it... Just don't know.
Hey, you pals who know the soft better than I, could you give some advices about the things to do/not to do due to the engine limitations and the correct options to take when people model with MAX ?
Thank you for help !