Here goes:
1. I'm going to guess that it's Godolphin Arabian. According to the General Stud Book (kinda sounds like an escort service doesn't it?) three horses hold the distinction of siring subsequent winners: Byerley Turk, Darley Arabian and Godolphin Arabian.

2. Formed in 1874 by Meriwether Lewis "Lutie" Clark, Jr. and the Churchill Brothers and opened on May 17, 1875

3. Sir Barton - Owned by Commander J.K.L. Ross, Trained by H.G. Bedwell and Jockeyed by Johnny Loftus