How many HD streams will I recieve?

You really won't know until the tech runs a test on your line during the install, but keep in mind that with the newer equipment U-verse has out now the older distance limitations can now be far exceeded.  Ideally you would want 4 HD streams of course.

What you could do is look around your neighborhood and see if you can find the closest VRAD to your home.  Keep in mind it's cable distance from that VRAD to your residence.  Mine is 3 streets over and I have a sync rate of about 51,000 and it shows me at 1100 ft away.

VRAD would look something like this: