It's good, the screen can be a bit small though. I initially got an Air then returned it for the new 16 inch, even though I didn't need its power.
It's hard to answer this question - good in what way exactly? I'm on a 16" M1 MBP, compile times are a lot faster than my intel machine but still pretty slow if I'm being honest - I know this is a focus point for Swift 6. A lot of the developer tooling has improved recently as well making the whole experience pretty pleasant.
It’s certainly doable with a little patience. I usually hide the nodes I’m not using to free up some workspace real estate. Obviously, everyone’s experiences and tolerances will be different, but I recommend giving it a shot. Are you able to use an external monitor with your Air?
I'm good with the screen size. I love it in fact.. It's the perfect form factor for me. I've got a larger pro from work, and much prefer my air.
The only caveat, is harddrive space. XCode is a hog, so opt for the larger HD.