1-yes, initial draft will be ABBA
2+3-yes, a player can be taken by any team that they played for, or that made a pick before they were selected. In your Ron Harper example, he could be drafted by BOS, GS, IND, NYY, PHX, and DAL in addition to CLE, LAC, CHI, and LAL.
4-for now, I would like to shoot for 24 unique owners--perhaps overly optimistic, but I do think once people see how this can really play out, it will gain some momentum