Good question about Ebenezer--some of the family researchers list him as one of James Sr's children, brother to Matthew and James Jr. Although I haven't seen any real basis for this claim, it's possible because he ended up in Christian County (formed from Logan County) KY.
The land that James Sr. had in Spartanburg County SC, dating from 1760-1770, was probably one of the grants given to anyone who would settle in that frontier area. As I understand, there was a basic grant that could be increased for each member of the household, and getting the extra acreaage required naming the household member(s). It may be worth the time and trouble for one of us to search through the SC land records to determine if James Sr. claimed land for his children.
Several of the families that settled near and intermarried with the early Alexanders of Henry County TN came there from Christian and Todd Counties in KY.