I've been forced to use site:news.ycombinator.com in Google. Could you just use Google CSE (http://www.google.com/cse/). Just a suggestion. I am probably the 20th person asking for this. Let me do search...dohhh...
I don't think there is anything for comments, but for favorite posts, look at "saved" in your profile. It isn't quite the same feature, but works as a lesser favorite.
