Drag files into message

Hello,

I've noticed that sometimes I drag a file into the current message window,
but sometimes WLM will try to send it as a file and some other times it will
"share folder". How do I turn off this second behavior and set "send file"
as default action for any message window?

In the new Windows7, WLM comes in the taskbar as default. Is there a way to
make it appear in the system tray only? I would like it to have the same
behavior as it does in Vista.

Thanks.