1) What would we name the campaign? I'm not fully certain, but I think Living Eberron is the name used by the RPGA, and even if not, it sounds a bit too official.
2) Where would the "base" be? Sharn? Stormreach? Possibly two bases, one in Sharn, one in Stormreach? (Base meaning the city/tavern where the adventurers start out. In Living Enworld, it is currently a tavern called the Red Dragon Inn, in the city of Orussus.)
3) Should evil characters be allowed?
4) What about subraces? Disallow all except the "powerful" subraces (drow, svirfneblin, duergar), meaning that they would not exist?