Hi Tailwinds, some stuff to add...
Sharing a cockpit is in the multiplayer menu. You can see where it is just by setting up a multiplayer session and in there is a check box for "Share My Cockpit" and you can even password protect both the multiplayer session and anyone able to share your cockpit.
Once you join a cockpit or someone joins yours, you can move around to the available positions. Sharing a checklist would actually be easy if you both have a copy of it in a desktop window since you both could pull it into the cockpit with FlyInside. They would each be in your own desktops/cockpits but you could both refer to them, discuss them, etc. Maybe not exactly what you had in mind but workable.
You definitely want easy voice communication when sharing cockpits. FSX allows voice but a program called TeamSpeak is much better, clearer, and very easy to use. We also have a TeamSpeak server (details in a thread in the Lounge on multiplayer flight) but there are lots of others that you can sign into as well.
I believe control of the airplane is "owned" by the person who shares the cockpit and the person who joins has to wait for the owner to allow them to fly the plane. Hazy here because I haven't done it much in the way you describe but details would be easy to find in a web search. But I do know sharing a cockpit is huge fun to do a ride along and I got to do this recently with an aerobatic team during a practice session:
https://youtube.com/watch?v=vGgP_acIeCYI wasn't trying to fly the plane but was instead just along for he ride but you can see the possibilities. Also, the other pilots were flying monitors while I was in VR. So we had a multiplayer session, mixed between VR and monitor, with a shared cockpit happening at the same time. When Tony, Bruce, Axel, and I fly, we are also mixed between Vive and Rift since I have a Vive and they all fly Rifts.
Shared cockpit is just amazing if you can do a ride along with a formation team. One of the most fun flights I've ever done. You just need to have the same kind of airplane in your aircaft library or else you'll see a formation of one of the stock aircraft. But shared for flight instruction and pilot/copilot complex aircaft would be a lot of fun too. Only thing is on many planes there are no pilot and copilot figures so the cockpit is a bit eerie at first.
On the orienting real life cockpit controls to match the virtual world, Sharkku is right that it is difficult but maybe worthwhile if you only fly one plane. Second best is to use a stick/yoke/throttle with lots of buttons/switches/knobs where you map common functions so they are handy and just don't mind they are out of place. There have been some people experimenting with green screen techniques to blend real and virtual worlds so you see all the stuff you want to see that is real and the rest of the cockpit and outside are virtual. There is a post here somewhere that shows an amazing video some guy did where he has a soda bottle, his own steering wheel, and other things in the virtual world with him.
It's an exciting time and some things have just been here all along waiting for other tech to catch up. Shared cockpit is a blast and so is multiplayer. Have fun!