The bank I work for is evaluating a possible acquisition of a bank. Are there any checklist or instruments I may use to perform a complete Due diligence of all regs.

Tall order. Given the usual limited time to do due diligence you can't realistically cover "all regs." So keep it risk based. Assuming the target is a community bank:

Start with looking at recent compliance examination reports and audit reports for quick identification of compliance trouble spots. Do some deep dive reviews in higher risk areas like flood insurance, BSA AML, OFAC, etc. The AML risk assessment should identify high-risk products and services that may hint at their overall compliance risk profile.

Ask for the number and dollar amount of HELOCs, Section 32 loans, ARMs, number of MSB customers, number of CTRs and SARs filed. From there you can tailor more deep dives if the numbers indicate higher risk.

I would also review some final TILs against APRWIN (double check the fees), and verify their knowledge of rescission rights.

Also ask for the policy and procedures manuals and exception reports, lending and deposit, and customer complaints.

http://www.bankersonline.com/bankerstore/index.php?main_page=product_info&products_id=383

Managing Compliance Risks in Mergers & Acquisitions

Review a sample of the Flood Determinations for completeness and accuracy. Look at the CRA Public File for skeletons. Evaluate the training reports for required training, and especially required not attended training (may point to other issues).

See who their vendors are - you may find that you use some common vendors which may make your due diligence a little easier - for example, if you both use the same vendor to do flood zone certifications, credit reports, etc., you will have a better comfort level than looking at vendors you've never heard of!