Hi Chris,
welcome here! But you did not search. Do a search over "spamassassin autolearn" for your first question and simply read the docs for the second question.
I do not want to be unpolite, but the spirit of GPLed Software in general and SME in particular is a little bit different.
Do not expect entry-level support here and first try to find the answer yourself.
Good luck with SME in the future. You made the right choice.