Aid To Bible Understanding was reworked into The Insight on the Scriptures. I don't know the differences between the two volumes and the "Aid" book as it was called. The changes in content were negligible as I understand.The Aid book had few illustrations, tiny type and bible type paper so it could be one book.
Three Worlds likely was Barbour's work but Russell certainly claimed to have vouched for it's content. It seems little more than a curiosity now..