* Funds are "surrounded by temptation" - barrister (Recasts with NAB compensation bill, pension misconduct by others): SYDNEY (Reuters) - National Australia Bank (NAB.AX) will compensate thousands of pension fund customers who had paid for advice they did not receive, Australia’s financial-sector inquiry heard on Monday as it turned its sights on the pension industry. The first day of hearings into Australia’s A$2.6 trillion ($1.9 trillion) pension system heard that a unit of NAB, the country’s fourth-largest bank, had charged customers “plan service fees” for advice they did not receive.