Couple of questions:
A) If the grammar forms a tree will it be more efficient? (versus all combos)
What do you mean by efficient in this case? Do you mean will it result in a smaller amount of code in your app, or will it be more accurate for the user, or will it be faster to return a result, or…?
A number of the first words would not have following words assuming a restricted grammar (TWO ZERO not allowed for TWENTY)
I’m not quite seeing the question in this one, can you clarify?