Floboy answered your questions, but I'd like to point out something. はず (hazu) has a lot of grammar patterns. Examples: 1) はずだ (hazu da) - In this pattern, the speaker has information that makes him expect the event. 電車は１２時に出るはずです。 "densha ha 12ji ni deru hazu desu." - The train leaves at 12 o'clock. 2) ないはずだ (nai hazu da) - Weak negative form 見つからないはずだ。 "mitsukaranai hazu da" - I shouldn't be able to find it. 3) はずがない (hazu ga nai) - Strong negative form 彼がそんなことをするはずがない。 "kare ga sonna koto wo suru hazu ga nai." - There's no way that he'd do such a thing. 4) はずはない (hazu ha nai) - The speaker doesn't exclude the possibility, but he thinks that it isn't likely to happen. 忘れるはずはない。 "wasureru hazu ha nai." - It isn't likely that he forgot.

"nareteru hazu" means "should be accustomed to". "hazu" is for "should" or "it is expected that". Another example: "kare ha kuru hazu desu." "He should come."/"I expect him to come." "konna mazui tabemono wo taberu hazu ga nai." "It cannot be expected tio eat such an unappetizing dish."