Take a look at Andy Zavoina's tools for starters. His audit workbooks, for example, touch upon some of the subjects that would need to be addressed, such as Reg B and Reg Z. You can link to the tools on Andy's Page from Banker Tools.
You might try www.ginniemae.gov-guide-guidtoc.asp. At Appendix 9 is the audit guide your external auditors will use if your bank has a full scope audit annual audit. I believe there is also guidance from HUD, but I don't have that e-mail address. It might be under hud.gov.