You and your friends should all be able to dine in the CCR.

As for having them all in the F Cabin at the same time I guess that would depend on a number of factors... how many other F passengers, if it's a day flight or night flight, etc. I would be surprised if they were all allowed in at the same time, particularly if there are other passengers.

And yes, the 2-4-1 must be on BA metal.