Fyellin, thanks for the encouragement, but my comment above wasn’t really a plea for help; I was simply highlighting the paradox of the puzzle’s construction. I cold-solved all but two clues, worked out the likely message, hoping that the unsolved clues didn’t have extra letters, then constructed the grid with ease based on the sequence of answers with extra letters.
I think the form of the final grid is very unclear. Wiki seems to suggest the forms recommended by an international scientific body, which seems to be what AlHearer has in mind, but are the other forms ‘unscientific’? Whether they are or not, the grid would look far more interesting with them.
AHearer, to address your point about abbreviations consider an analogy in a completely different field: Fe is the xxxxxx for iron, so I don’t see a contradiction in using the forms you allude to.