I picked the garments up tonight and had my wife ship them home. I can't say I'm thrilled.
With respect to the overcoat, the fabric and fit turned out better than I expected. However, he screwed up in two significant respects. First, at least the lapels, and possibly the whole coat, are fused, despite my having given him instructions in Vietnamese to produce a canvassed garment. Second, the lapels are machine-stitched about half an inch from the edge, notwithstanding a lengthy discussion (by way of pantomime) about pick-stitching them at the edge. This gives the overcoat a very casual look, and one that is in any event not at all to my liking. Also, based on the 90 seconds during which I wore the coat, the lining seems to breathe very poorly - however, I will withhold judgment until I am wearing the coat on a day when it isn't 100 degrees outside and I am not drenched in sweat.
The shirts fit well, and very similarly to the shirt I gave him to copy, with one exception: the collars are too big. I will have to wear them open-collared. Less crucially, he used a collar style different from that of the shirt I gave him to copy. On the plus side, without my having asked, he pattern matched on the sleeves, which is great. He also, as requested, made the collar stays removable.
For $150, I did fine. I may even have done well; perhaps my expectations were just too high. However, I can't say I'd use this guy again - I'd rather pay the extra bucks and get precisely what I want from W.W. Chan or Jantzen.
Thank you, in any case, for the recommendation - and for the offer to translate! I could have done far worse.