[fface]

Hi susan,

1.Are incredibly and extremely hot hotter than very hot?

2.Does 'so' also work in the example you gave?
A : I was so nervous before the interview.
B : You were so nervous? Why were you so nervous? You were the ideal candidate!

3.J:Are you free now?
T:No, I'm very/so busy.
J:Why are you always very/so busy?
Do very and so sound natural in the context?

4.When I take a test and say "It's so easy!"
Does 'so' connote a surprise? i.e. It's much easier than I expected.

Many thanks!