Not the pyramid of doooooooom 
I agree. I vastly prefer async/await to callbacks - as lasjorg mentioned it’s very helpful for clean and maintainable code. Additionally, using await allows you to store the return value of a promise/function in a top-level variable which can be passed around wherever, whereas callbacks scope the return value to within the callback function.
You can - I use async/await with my express apps without issue.
I would definitely recommend against this. I would choose one or the other for a project, or you’ll end up creating additional confusion for yourself.
There are certainly aspects of the curriculum that aren’t up to date. The challenge with technology is that it is ever evolving, which means maintaining information on the latest and greatest is a lot of overhead.
We are, however, working on some significant revamps to our curriculum, which you can read about here: