In ch.19, we are told that "Mr. Collins made his declaration in form". Does that mean that:

a) he proposed as Elizabeth and Mrs. Bennet had been expecting?
b) he proposed in a correct, formal manner?
c) something else?

Before Mrs. Bennet leaves the room, he tells her "May I hope, madam, for your *interest* with your fair daughter Elizabeth, when I solicit for the honour of a private audience with her in the course of this morning?" I read that as Mr. Collins asking Mrs. Bennet to use her *influence* with Elizabeth to persuade her to accept his proposal. Is that right?

In ch.20, Mrs. Bennet tells Charlotte: [Elizabeth is] "looking as unconcerned as may be, and caring no more for us than if we were at York, provided she can have her own way." Was "caring no more for us than if we were at York" a common expresion?