The note about Field's Division getting ANV 4th Bunting flags came from Howie Madaus' research and was most likely based on a survey of surviving flags of the pattern. I have not done anything like that myself but I would bet that the flags of the pattern with known ID came mostly from this division.
With regards to the 15th Alabama's color bearer I have heard that he was buried with the flag he took up Little Round Top and I do not recall hearing anything about their Appomatox flag being buried with him - but then again I have not thought about this flag in some time.
Sorry not to have more help. Perhaps Ken or Tom can add to this.
greg Biggs