These are wonderful!

I'm no expert on this, but I think that the buttons on the officer's tunic would be grouped in two's or three's if he were a senior commander such as Armistead. I've attached a photo of John Bell Hood's uniform as an example. Also, Armistead was both bald and bearded so maybe an alternative head would be a nice option.

On the battle flag, they were often relatively small and square. I've attached some photos I took in Richmond a few years ago in case they help.
Best
Gerry

(Note: I think that the photo of Armistead is a pre-war image showing him in his US Army uniform - the source is Wikipedia)

Thank you! Very useful info. Don't worry about flag, it is just render and real flag will be right shape and size. And may be manufacturer wants new head and tunic. I should ask him.