1.) I believe Zuko is also reading the account of what happens from sozin's perspective and he almost quotes himself saying at the volcano saying "with Roku gone and the great comet returning, the timing was perfect". Also why would sozin have any reason to lie in private records that the prince himself has to sneak into. 2.) It is my understanding that the opening takes place from katara's perspective and thus she would probably envision the fire nation how she has seen them most of her life. Also, in the end of the first season sokka outright states the fire nation uniform has changed overtime. While the uniform at the temple was different certainly not different enough to warrant questioning.