The 4.8 fan should bolt right up to the water pump pulley of the 05, every one that I've seen has had the threaded provision for it, but double check just to be sure.

Yes, the 6.0 uses a 34" radiator as opposed to your 28" radiator, I believe that all trucks that came with efans also have the 34" raditiator, so you'll need the 34" rad to make the efans fit your truck. I got my 34" rad from the radiatorbarn.com for around $265 shipped IIRC.