Does the renewal require prior Board or Board committee approval? - Yes.
If prior Board approval is required for the renewal, what are the implications of the common Bank practice of back-dating renewals? i.e. approval dated May 15th, loaded on May 16th, backdated to March 15th? - You are likely to get many opinions on this. It is definately a process/procedure problem, but as the funds are already out and you are not entering the renewal until after the approval, you should be okay. However, you'd better be able to document/prove that posted renewal date or you've got a big problem.
Also, does the requirement to re-approve revolving credit lines every 14 months apply to cashlines used only for overdraft in accordance with the exception? - In my opinion, no.
What if the aggregate amount of cashlines used only for overdraft exceeds the $5000 limit? - In my opinion, YES.