They're really not that sqeaky/loud but I'd never take anything that makes noise like that on a plane so my kid could potentially annoy someone but that's just me. There are worse things you could take on a plane if you really have to.
They are both made by TOMY. The Hide and Squeak eggs are the newer version and the little chirpers are the older version. The only difference is that some of the eggs have a different inside color and facial expression.
That depends on the child. I think so. My daughter turned 2 last week and she still plays with it. She still gets confused with the egg tops & they frustrate her, but I think it's because she got it when she was 20 months and is over thinking it. We can add those back into play later on probably when she doesn't over think as much. Also she could probably use them later on playing store and having a carton of eggs. :-)
This is one of my grandson's favorite toys. He's still too young to identify shapes yet, but this is a toy that grows with him. The shapes are star, circle, square, heart, triangle, square cross...and the colors of the tops and bottoms of the eggs match. Great toy!
Yes, the toy is very cute and easy to handle for little hands. They are color coded as well which makes it a game to match them. I gave to my great-grandson for Easter he was 15 months old and loved them and got the game quickly.