Nope, one key per letter. T9 uses an internal dictionary to figure which word you meant, with some memory for preferred words when there's multiple matches and adding custom words.
Exactly this, and occasionally you'd have multiple words come up for the same number combo, but in a consistent manner where the user could learn how many times you needed to hit the 'next' button to get the word you wanted.
The phone I used t9 on the most had the "next" button on the * key, an option to sort based on frequency, and replaced the word with "spell?" before cycling the list allowing you to manually edit the word and add it to your dictionary. I assume disabling that sorting function was preferred for people blind-texting.