are Y!Updates firehose semantics defined?

Hi,

Looking for answers to the following questions.

1) If one invokes the firehose yql call in a loop, are we guaranteed to get different data set ever time e.g., in the first call we get "x" updates and in the second call we get "y" updates where Intersection(x,y) = null?
2) I was under the impression that once you connect to Y! servers you keep getting the data back as long as one holds the connection open, doesn't look like this is the supported semantics.
3) Looks like the firehose API supports pagination parameters? what is the semantics of such pagination do one get to go back in time and get the data? is it allowed? Looks like a wrong capability for firehose like API's? I guess it is the result of YQL abstraction!
4) Does it have twitter or facebook updates too? especially if Y! accounts are linked to facebook.

I guess I will buy a lottery ticket if I get a response :-) quickly i.e.,.