For your first point, probably yes. Keep in mind, the blades are twisted slightly from what they would normally be on the B-29 aircraft. I think the tips of the blades are also squared off, as the one in the picture of the aircraft has somewhat round tips. But the tunnel has flow straightners (which you can see in the pictures that looks like honeycomb). All props, no matter how modern, will cause swrill in the air behind them.Would a more modern propeller cause less turbulence? Might turbine blades otherwise excel in a wind tunnel?