By Deepa Seetharaman and Paul Lienert DETROIT (Reuters) - The U.S. Department of Energy's (DOE) 2009 decision to grant Fisker Automotive a $529 million loan will be heavily scrutinized on Wednesday during a congressional hearing that is being held as the automaker verges on collapse. Among the key questions is whether Fisker's prospects were strong enough at the start to warrant the DOE's backing, which helped trigger a flood of private financing for Fisker. Fisker's failure to make a payment on the DOE loan Monday is the latest of its troubles. ...