Idioms are basically phrases which have a meaning completely different than their literal definition. E.g. It's raining cats and dogs (we know it's not literally raining cats and dogs, but through usage we've established that it means it's raining severely).
3. Idiom: weight of the world
Meaning: a heavy burden.
4. Idiom: keep (my) side of the bargain
Meaning: follow through with an agreement.
5. Idiom: flying high
Meaning: either to be successful or in a state of ecstasy. In this case, the latter. (Effie is excited.)
6. Idiom: rub the wrong way
Meaning: to annoy.