l'expert en cocktails

I don’t think so. The expression is “(un/e) expert/e en qqc” - an expert in something,  not (un/e) expert/e de qqc - an expert of something.

Effectively the same as we say in English.

Hi Mary Anne,

I haven't carried out the exercise.

However, given that "Apéro en terrasse" suggests taking an apéritif "in the location of a / the terrace" I can't see how "de" would make sense in this context. Perhaps I'm missing your reasoning?

Jim