Exterior OSB wall cladding.

Hi, I am about to start framing my exterior walls and have a couple of questions. Do i need to caulk all the joints in the two layers of exterior OSB or will this be sealed when the junctions of the inner layer of OSB and the studs are sealed. What screw centers are recommended or screwing the outer leaf to the studs. Colin.

We install an exterior grade nail with an air actuated gun. It's more cost effective then external screws. And easier and less time involved:)