If it were me I'd take the two baffles from the bottom on the right, invert them (make them top down) and put them on either side of the left baffle. Probably a good idea to leave one in the third from the left's spot too but not needed.
So far as spacing, it really depends what return you end up going with. If they are too close together for the flow, they won't do their job and allow micro bubbles to rise out of the water. Too far apart and they just eat up realestate.
As for the 10" height, do you know what skimmer you're going with yet? Some might not like that much water, but you could always build a table to raise it up if need be.
Starting to come together eh?
Chris