Have you looked in the settings at the keyboard control options? If a key binding doesn’t already exist, you should be able to create a custom one for all the controls. I haven’t really explored the A310, so not familiar with its specifics. Hopefully someone with more knowledge can help you with that.
Now you are getting into some of the more nuanced territory. If you are creating a flight plan in the world menu, then it should directly import. When you jump in the cockpit and get everything fired up, it should populate in the flight management system (FMS) so all you need to do is turn the autopilot on. NAV (or LNAV) mode tells the plane when to turn left and right based on waypoints or GPS direct route. VNAV controls the vertical position based on altitude restrictions. HDG mode aims the plane at a given heading and doesn’t change, and also doesn’t correct for wind drift. Altitude hold (ALT) keeps the plane at a specific altitude and you would use vertical speed or flight level change (FLC) to initiate a climb or decent. Not every plane has every option, and there can be minor differences in how they operate in each specific plane. This is where searching for plane specific tutorials come into play.
You can also set up a flight plan from scratch in the more advanced aircraft. Again, this is very plane specific, so this is only generalized info and you’ll want to search for tutorials specific to what you are flying for more info. You select your airport to depart on the world map as usual, either ready on a runway or cold and dark in a parking spot. Once fired up, there’s often a boot sequence to wait on, then position initialization you have to set to confirm the plane’s location. Then you enter the 4-digit code of the origin and destination airports. Some aircraft require little else, some want you to enter departure and arrival routing for a specific runway (SID and STAR respectively). I don’t have a great video on this off hand because I more or less figured it out by trial and error after reading a lot. If the CJ4 interests you, I did make this video to address the changes of the avionics update as it applies to casual fliers that don’t care to be super strict about everything. It’s almost two hours long, but covers a lot, including starting cold and dark, creating a flight plan from scratch in the FMS, and navigating with the autopilot. I tried to keep it easy to understand and address new pitfalls like the dreaded discontinuities in a route.
I don’t really consider the sim to have a co-pilot, at least not in the traditional sense. There are some “co-pilot’ish” accessibility options, but I find I prefer to just do everything myself. If using the autopilot system, there isn’t much to do most of the time anyway. Lol