Depends. This is highly dependent upon the age and depth of the amblyopia. Generally the time varies from 4-12 hours or more per day. The most important thing is to not induce amblyopia in the better seeing (covered) eye!
It depends. On multiple factors including your age and degree of amblyopia. Usually a patching regimen is recommended that will strengthen the amblyopia eye without risking the good eye becoming weaker. Discuss with your ophthalmologist.