The ATC isn’t great, so I’m not surprised you’re having issues with it. I haven’t had the climb to stupid heights after entering final approach, but I’ve heard of others having that issue. Not sure why it happens. A lot of people will ignore and not use ATC due to various problems like that.
As for which way to learn, I guess it depends on how much realism you are wanting. If you are wanting to keep it realistic, then yes you would want to start with simple props and work your way up. Personally, I didn’t do that. I’ll occasionally fly different aircraft just to bang the stick around, but my favorite is the Cessna CJ4 business jet. So what I did was jump straight to it and just learned what I needed to fly it competently. If you know there’s only one or two planes that interest you, then I would say have at them and learn all you can about them. When it comes to the various systems, there isn’t much comparable between something like the Cessna 172 and an airliner. Even the flight dynamics are wildly different. So my opinion is why learn the 172 if all you want to fly is something like 747? It’s not like you are putting real money and lives at risk jumping into the deep end, and the only downside is the learning curve you’ll go through anyway starting with a 172. Obviously that advise doesn’t work in the real world.
One thing to note about the A310 is it is a “study level” aircraft. Most of the others have simplistic controls and many inoperable functions, but the A310 was added last year for pilots wanting extra immersion without going to one of the third party offerings. As such, it’s going to be a much harder aircraft to fully understand. I just want to make sure you temper your expectations accordingly for that one. The CJ4 was one to get the avionics update, and it’s now much more in depth when it comes to flight planning and working with the computer inside the cockpit. It gave many of us a lot of frustration, but I can help you get acquainted with it if you need. Helicopters are also just plain difficult to control, to the point I think they are not modeled correctly (I.e. Spinning out of control regardless of control inputs). It can be done, but takes a lot of work and tweaking controller settings.