Searching just friends should be useful, but I don't understand the requirement to give access to my twitter account. In fact, I ended up not trying it.
The only way to access your personal twitter stream is via authenticated access, like any other twitter client.
Only if my tweets are private, I should think. There are public methods for getting a list of people I follow, and public methods for getting the tweets of any person (except for private tweets). In combination, these two should make my login credentials optional.