Terms of a $325 million settlement between Ameriquest Mortgage Co., the nation’s largest subprime lender, and a multi-state negotiating panel could provide a blueprint for ethical business practices that state regulators would expect subprime lenders to adhere to in all future lending, according to compliance experts. More than half of the 49-page settlement announced jointly by state prosecutors on Jan. 23 dealt with specific “injunctive relief” reforms Ameriquest has agreed to implement in order