[propbeanie]

From an SH4 perspective, but I am reasonably certain the SH5 uses the same type configuration, though it might add script-based configurations, so be sure and check for that, gap. In order of your list:

1. 1. Have not attempted to observe that. Interesting question, though they do seem to be capable
2. A strange set of circumstances, this one is (yoda-speak)... If you create a group with waypoints, they "follow" the leader of the group, just like ships, yet they do act somewhat independently after the initial phase of attack. As for the "spawned" planes, I have seen what appears to be a group of two planes act independently, with one (the closer plane) of the two attacking a ship, while the second does not (distance or "visual"). So again, They act like a "group", but they will seemingly act independently of each other, though if the one plane doesn't attack, the one that does will generally only do one "run", and then rejoin its companion and continue on its course. If both planes attack, then both will continue to attack until they run out of "ammunition", or get shot down. Short answer: I do not know... lol
3. Using independent "AirBases" with different AirGroups might be one way, but in SH4, the AirStrike config is the only file controlling what the percentage chance of a night attack is... I don't know if maybe a script in SH5 is available for that??
4. Yes. You want to set the spawning "AirBase", whether carrier or land-based to "Expert" (4) in order to have "Expert" planes. Anything less than an "Expert" plane usually results in crashes with dive bombers, or with turns. Even at "Expert" level, planes do not fly very well... but they can drop a bomb down an open hatch at 500 foot altitude while flying at 312 knots while flying upside-down... Luke Skywalker style...
5. The easy way to "predict" which loadout will be used is the "Default" designation in the config and equipment files. Again though, I don't know if SH5 scripts can change that?
6. The game expects one group to end before the other starts, and that they are sequentially set in all manner.
7. In SH4 this works, and I'm sure it does in SH5 also, in that anything with a "carrier" designation can "launch" or spawn an airplane, which generally takes roughly 20 minutes to occur (20km). So Type=8 and Type=9, as well as Type=18 and Type=19 can spawn airplanes. You do have to have properly configured AirGroups for them, with valid air platforms.

I am 99.9% certain there are more / better replies that will be forthcoming, and from SH5 people...