* U.N. workers help evacuate stranded Palestinians
* Snowfall paralyses parts of the West Bank and Jerusalem
* Israel opens main crossing with Gaza
(Updates with evacuation toll tops 5,000 wraps in West Bank, Israel snowstorms)
By Nidal al-Mughrabi
GAZA, Dec 14 (Reuters) - More than 5,000 people have been evacuated from flood-damaged homes in northern Gaza and at least one person...