Although mortgage market watchers cautiously expect President Obama and the lame-duck session of the 112th Congress to come up with at least a stop-gap deal to avoid the looming “fiscal cliff” at year’s end, building uncertainty among homeowners and potential borrowers as to whether important mortgage tax deductions will exist in 2013 threatens to thwart housing’s fragile recovery. Unless Congress and the president create and sign new legislation to change existing law before Jan. 1, 2013, taxpayers are poised to be hit with a massive combination of expiring tax breaks, tax hikes and deep, automatic federal spending cuts. A report last week by the Congressional Budget Office concluded that a failure to avoid the cliff would push the economy back into recession with the unemployment rate shooting up to 9.1 percent by next fall. Fitch Ratings warns...