Hey Jessica - thanks for posting your question here!
For your first question, it should be possible to search even within collapsed content via the spotlight search feature (the little magnifying glass in the upper left). This search tool does have some limitations, but works well for single (or few) search terms. That said, if you’re finding that this tool isn’t working for you, definitely let us know so we can look into it further.
As for the collapsing/expanding point: unfortunately, we don’t currently support this in the product. But I do think it’s a great idea that could be useful for many. I’ll go ahead and add this one to our feature request tracker. Sorry for the inconvenience in the meantime!