Thanks! Once you sign up at www.hashfav.com, you can start curating other people's Tweets by adding the HashFav tag in your reply to them. For example, I curated all of these startup advice Tweets by adding "##startupadvice" to my reply. You can also curate your own Tweets into collections by adding the HashFav tag.
Yes but the reply Tweet doesn't have to be limited to the HashFav tag; it can be embedded in the reply similar to the hashtag (e.g. "wow, this is ##cool"). Replying to the Tweet also serves to notify the author. However if you want to be stealth, you can copy-paste the URL to add a Tweet into a collection.