I can't find it anywhere on their website (which does seem a little shoddy to me, too), but at what rate do they exchange MilesBar miles for Mileage Plus or other major program miles?

I seriously doubt it's 1:1 based on their prices for free travel (50000 miles to buy a ticket through them), becuase no one would use their miles, but buy 2 25000 mile tickets from their own carrier.

Is there a cost for transferring miles to your FF account? Is there a limit?

Sorry, this one sounds a little too good to be true (which I would have believed from a dot-com 6 months ago, but not anymore).

As a side note: I also don't understand why you are disincented from referring people to the paid Platinum option.