As far as the axis rotation trick goes, like I said, it sometimes works, it sometimes doesn't. (Depends on difficulty and opponent.) It does look cool to watch, though.
I use a gamepad when I fly...not quite as realistic (if you can be realistic when you're flying a fictional spaceship against fictional aliens) but the only trouble I ever have with it is when I want to communicate with my wingmen or need a rapid shield boost.
Re: Single or Double Shots
This is another case for the low-power guns vs. high-powered ones. Subachs don't suck much energy, so you can go rock'n roll with them for quite awhile, as opposed to a full load of Kaysers & Maxims. You really just have to plan ahead based on your mission's profile, and your ability to make your shots count.
Double or Single Missiles--again, it's a question of your mission, and your loadout. I try not to dogfight with missiles unless I'm up against the wall. Target locking missiles (Hornet, Tornado, Harpoon, and Trebuchet) are great if you can get that target locked--which at higher difficulties means you have to be at a distance. At close range, the only missile that's ever helped me out is the Tempest. You can treat that missile like a third bank of guns, but remember it's going to run out eventually, too.
Then there's the bigger bombs (Cyclops, Helios)...I almost always fire those off in pairs, just because of the reload time on them. If you're going to be waiting twenty seconds or more to fire off the next salvo, you might as well get the most out of it and fire off both shots.