OSLO, Dec 17 (Reuters) - Norwegian Air’s shareholders endorsed the carrier’s financial rescue plan in a series of votes on Thursday, one of several hurdles the company must clear in order to survive the COVID-19 pandemic, business news sites DN and E24 reported. The airline faces difficult negotiations with creditors in the coming months as it seeks to reduce its debt and liabilities of some 66.8 billion crowns ($7.75 billion), and must also find investors and lenders willing to put up fresh cash. ($1 = 8.6226 Norwegian crowns)