Ok - I'm fairly new to the forum and I'm not completely up on my terminology - what's an MGL?
Military
Great
Leader -- If an elite unit is victorious in combat, there's some percentage chance that you'll get one. Someone who knows more than I will have to fill you in on what the odds are. You can then use them to build armies, which you would load with military units, or you can use them to rush construction, which is usually used for small wonders, like the Pentagon, or Heroic Epic. They cannot be used to rush Great Wonders, like the Pyramids or Sun Tzu's Art of War.
If that's a shield bonus for disbanding - yes, you get them for disbanding naval units in towns (harbor or no) for building other units or items (naval, defense or construction - but not wonders, I believe).
No, it's not. See above. You get some shields back for disbanding units, but you are correct in that shields from disbanded units cannot be used for wonders.
I don't build a lot of artilary unless I'm sharing a continent with other civs - which I usually try to avoid or achieve. My strategy is to let them come to me over water, having a pretty strong navy and bombers in key areas.
On the offensive, I use transports and the like to secure foriegn cities and establish "bases", fortified with mobile units and bombers for defense.
So, long answer I guess - I'm more into using air bombardment than stationary.
When I said "artillery," I was using the term very loosely, beginning with catapults. You've got to build a ton of them, but a stack of cats goes a long way towards raising your kill ratio and the AI's loss ratio. Bombers come pretty late, long after you could be using things like trebuchets and cannons to lower your losses. Once you hit "real" artillery (to which cannons upgrade), they go to a range of 2, so your 1-move units can sit outside of the range of their 1-move units and pound them.
Nothing wrong with air bombardment, especially because in C3C, bombers have lethal bombardment. Redline the AI with artillery, then bring in the bombers to kill off as many as you can. Then kill the rest with ground units.
You'll have to remember to protect your artillery, but even if you have to transport them overseas, they're good for pounding cities. They'll even kill off population and destroy improvements.
Edit: And if you have taken control of the seas, build some carriers and put some of your bombers there. Carriers don't flip and they don't get taken by the AI's cavalry.