Our 4 yr old goes to the top step, grabs door handle and unlatches, steps down to first step and opens, walks in and closes the door. No falls or issues. How did he figure that out? I showed him once when he was struggling to get in. He has had it from there.
Also, no worries about letting air out because he doesn't spend any more time with it open than mom or myself. Why? We have explained, you close the door behind you.
Kids want to learn and be independent.
Only time we almost had a fall was when he was leaning against the screen door from the inside. He caught himself and hasn't made that mistake again. I explained the screen door latch and showed him that it wasn't very strong.
Teach, explain, make the most of teachable moments, treat them with maturity and don't coddle.
You may be suprised.