I don't understand your second questions, but as far as I know, every Fiesta have 7 airbags: steering, driver's knees, passenger, both side curtains and the seats. I know this was true of my 2012 SE, would be VERY curious it was not the case for the base seats of the FiST.
I don't know about putting the Focus seats in the Fiesta (other than it's possible), but if the plugs are the same, it's simply plug and play for the airbags, otherwise you might need an adaptor. I would imagine that they would be the same plug though...