Make sure that you thoroughly review the bank addendum and that it contains ALL the terms you want. There are usually areas in the document to fill in specific contingencies, amounts to be paid by the bank, etc. Although I have never found a lender that will negotiate the boiler plate language, they will incorporate all the terms of the original negotiated residential purchase agreement (RPA), as long as you point out anything that was omitted.
One of the main things contained in these addendums are shortened contingency times. However, in my experience, the bank has already countered these terms in the RPA in their counter offer, before they have you sign the addendum. The addendum DOES supercede similar terms in the offer, so make sure you get what you want.
If your are still uncomfortable with the addendum, have it reviewed by an attorney who specializes in real estate law. If you would like a referral, let me know. I work in the LA area and have some great contacts with very good real estate attorneys. You can contact me through my profile.
Enjoy your new home and Dare to Dream.
Real Estate Consultant
RE/MAX Palos Verdes Realty