Is there any regulation or specific thrift guidance that says that a financial institution must notify all consumer customers that they have a right to request the institution's underwriting policy? If so, can they get an abbreviated version?

There is an OTS regulation that the underwriting policies must be available for consumers. I believe it can be in a generalized form. (Don't know the cite.)

In the OTS Fair Lending book it states:

"Underwriting

Each association is required to have clearly written, nondiscriminatory loan underwriting standards available to the public upon request, at each of its offices."