4,Even though the noble was expected to read the letter at each performance
 even though = even if = though / although
at each performance = at every performance新概念英语2mp3下载

5, he always insisted that it should be written out in full.
insist: 坚决要求，suggest:建议， order:命令，demand:要求，require:要求
表示建议/要求/希望，和that宾语从句搭配，that从句必须出现should + 动词原形的虚拟，should 可以省略。
in full==fully=completely
 
6,  The curtain went up on the final act of the play and revealed the aristocrat sitting alone behind bars in his dark cell.
 on the final act == in the last act  最后一场演出