Mortgage lenders have courted realtors for decades as a source of borrower leads, but the days of donuts and golf dates have evolved into potentially more profitable – but more perilous – formal arrangements. When it comes to partnerships, experts say one size doesn’t necessarily fit all. In fact, lenders are pursuing a number of different avenues to get business from realtors. One well-traveled approach, taken by such firms as Cendant Mortgage and Wells