Well let me put it this way: The A-10C doesn't require a lot of skill for normal flight operations. Take off, Landing etc is all very straight forward, it's a very stable plane that forgives a lot of the usual handling mistakes a beginner might make.
That doesn't mean keeping a close formation or combat formation or flying basic combat maneuvers will teach itself but it makes it easier to concentrate on procedures and systems.
Regarding the L-39C Trainer:
It's a Czech trainer aircraft from the 70ies which means it features Soviet design philosophies like a free swinging nosewheel and steering with differential braking (which needs a lot of getting used to!) and russian navigation systems. And every gauge is metric of course.
Anyway, I think that multiplayer multicrew is fantastic, not only for flying COOP in a fighter jet but especially for training in an aircraft like the L-39C or C-101* in multiplayer.
*only the L-39C in 2.0.1 is working correctly right now, 1.5 should get the bugfixes for the L-39C this friday, no idea about the C-101 but I know AvioDev are working on getting multicrew implemented.
The way it works right now is that you either set the control priority in the editor to the front seat, the back seat, set the controls to equal responsibility or always require permission to take controls from the player who is currently in control of the aircraft.
If you just want to show a new player the game you set the control priority to the front seat.
That way you can handle all the systems yourself, let the other guy enjoy the ride and maybe give him a go at the controls once you're in the air. If he messes up you can simply take control away from him by pressing a button. Basically you're giving the other one a joyride.
For proper training you obviously want control priority with the instructor in the back - let the student handle the aircraft and its systems and only interfere if he makes mistakes that might get you killed xD
Anyway, so much about that. I'm very excited about this feature in DCS