Yeah, the mongoose documentation is lagging on some of these things, and unfortunately the solution is not very intuitive (comes with the territory when using something still going through rapid development and API changes on the way to version 1.0)
Meanwhile, this will do what you're looking for in terms of sorting:
db.model("Person").find().sort([['age','ascending']]).all(function(people) { });
As for the question about more complex nested relationships, if you haven't already, you may want to start with the excellent MongoDB documentation, specifically the articles on Schema Design, Advanced Queries and Dot Notation (reaching into objects). Knowing MongoDB inside and out should make navigating the murkier parts of mongoose a breeze.
Here's an example for finding movies by genre using $in:
db.model("Movie").find({ 'genres': { $in: ['Horror','Comedy'] } }).all(function(movies) { });