In response to your questions (from SEC-compliance perspective):
1) Qualification as a financial expert is determined by the board using their judgment and their interpretation of the requirements set forth by their respective exchange. For example, NYSE requires each audit committee member to be financially literate; and the financial expert must have accounting or related financial management expertise. NASDAQ requires the financial expert to have “past employment experience in finance or accounting, requisite professional certification in accounting, or any other comparable experience or background which results in the individual’s financial sophistication, including being or having been a chief executive officer, chief financial officer or other senior officer with financial oversight responsibilities.â€
2) SOX has a safe harbor provision so that a financial expert is not held to a higher degree of care or legal responsibility than other audit committee members. (Otherwise, people would be very reluctant to sign-up for the financial expert gig)
3) It depends. You may want to confer with your insurance agent and legal counsel on this matter.
Is your bank already a publicly-traded institution? If not, then you may want to also focus on the FDIC's audit committee and financial expert requirements set forth in Part 363 (see link below).
http://www.fdic.gov/regulations/laws/rules/2000-8500.html#2000part363.5