lion
Will fluxbb become Flarum ?
FluxBB is a separate software and isn't related (outside its developer) to Flarum. There will be converters from FluxBB to Flarum created when Flarum is stable, however.
How long is the wait for the Flarum realese ?
As long as it takes. Really, development has been moving at a steady pace recently, I would say the wait for a new release is going to be relatively short.
Is flarum as light wieght and last as fluxbb?
I've never personally used FluxBB, so I can't speak from experience. But Flarum is designed to be light weight and fast, with its extension system designed so you can add only the features you want.
Why doesnt fluxbb and flarum come with a private message system ?
There is an extension for Flarum called Flagrow Byobu that offers private discussions. Eventually, Flarum may write its own Private Messaging extension, after a stable release.