I'll give my question 2 more days, then I will answer it myself, and someone else can ask the next one. I'll also give you a bit to go on Fin077:
1) and 2) are the extremely obvious ones you already have (Which I assume are Tiki Barber (brother Ronde is a CB for the Buccaneers) and Eli Manning (brother Peyton starts at QB for the Colts).
3) Will (assuming he plays for the Giants, and his brother is active for it) play against his brother twice this season.
4) Is not a starter for the giants, but his brother starts for another NFC team.