Also, for the cannons on the X-Wings to converge properly so you have any hope of shooting down what you're targeting, you have to reorient them to focus on a specific distance immediately in front of the X-Wing. Closing the S-Foils means there is no focus anymore, and your shots are going to very oddly wild.

Actually, there would only be a slight reduction in the effective "focus" of the weapons, as they are still mounted the same distance from the center-line of your ship, still firing in the same general direction, just with less "spread". At optimal range (the range that they all converge- if you have your weapons set-up for that), they will still converge at more or less, the same spot. Beyond that specific point, the beams are actually spreading out, making them less effective. Keeping them aligned directly forward would give you slightly less effect at optimal range but would otherwise be almost as effective at any range, as they would have the same "spread" at all ranges.

It is really a toss up. In WWII, some pilots liked their weapons zeroed to converge at a specific range, to maximize damage and others liked them set at "factory zero" to increase the chance of a hit at any range.

At any rate, I'd think that the technology of SW would allow for slight adjustment of the weapons aim point without a change in ship's vector (ie. the weapons are somewhat "steerable"), probably controlled by the ships on-board fire control system. In fact, if you watch the Battle of Yavin scenes from SW IV/ANH, Darth Vader's shots seem to track on his targets (Biggs, I think), without him adjusting his ship's flight path, so his guns, at least, do seem "steerable". Maybe, that is what TL does?