I assume this is a fixed rate. You must state the APR, using that term. (you can also state the rate) Mentioning the term (48 mo), triggers other disclosures. See section 226.24 of Reg Z.
2nd question - If you are adv the rate discount, then I would footnote the fact that the cust has to have automatic pmts to get the rate.
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Opinions are my own and not of my employer.