As for the turrets - forget about them. When the WCIV video was written and filmed, they'd hoped to have a "turret skimming" mission where the result would depend on how many of the Vesuvius' turrets you're able to destroy. When it came down to doing the actual gameplay (which is perfected after the video), they didn't have enough time/desire to redo enough of the engine to allow such a mission. Just kill a bunch of Hellcats, and the game will go on.
(They eventually did get the turret mission thing right - they planned for it specifically when they did the WCP engine...)