Question about numbers

Literary Manuscript (novel) Question:

Question 1:
I want to put the ages of my characters inside parenthesis at the beginning of my novel, so can I say?

...but suddenly Abel Simpson (thirty-three) showed up in the blah bla. or ...but suddenly Abel Simpson (33) showed up in the blah bla.



Question 2:
I always follow the rule where from 1-99 the entire word is written,

Question about numbers