The info you give for Robert B and Sarah A. Dotson is correct.They were my husband's great-grandparents, and William H was his grandfather.(FYI, the 6th child James died at about 4 months old.)However, in Robert's obituary it says he was the son of "___ and Elizabeth (daughter of James and Mary Clinton Luster)".So we know his mother's name was Elizabeth, not Catherine.Also, Robert was born in 1840,. but the census records you list would have him born in 1843.We have found several records for a Robert M. Dotson born 1843 in Crawford County, who coincidentally married a woman named Sarah B.
We have found a Crawford County marriage record for David Dodson and Elizabeth Lester (possible mis-spelling?) approximately one year before Robert was born.But we have nothing to confirm that they were Robert's parents.We also show a David Dotson and James Luster listed just one line apart on the 1840 census for Merimac Township, Crawford County, and David's listing shows a female age 15-20 and a male under 5.Again, interesting but no firm connection.
Unfortunately many of the Crawford County birth records have been lost due to fires and floods, and Robert's was apparently one of those lost.