WASHINGTON (Reuters) - Jack Lew, President Barack Obama's pick to be treasury secretary, on Wednesday fended off criticism about his financial experience and tried to find common ground on tax reform with lawmakers considering his nomination. Republicans on the Senate Finance Committee blasted Lew with questions about his investment in a fund linked to the Cayman Islands and his work at Citigroup, especially a $940,000 bonus he received just before the bank got a taxpayer-funded bailout. ...