It's NVG589 (not NGV) and there's tons of info over on the Uverse forum »
AT&T U-verseWhile I do not use one myself, I've heard 1) it's mediocre; not great but not bad. 2) Not really. 3) No restrictions. 4) Not overly, but if the ballast generates a ton of noise it could hurt speeds slightly; bulb orientation does not affect this.