Is "It's 8am in Mr. Feliks's Homeroom" a sentence?

Yes

Explanation:

This sentence is grammatically correct and makes sense.

yes but also no

Explanation:

it needs to be a little bit longer

themselves

an intensive pronoun is a pronoun that ends in self or selves, such as himself, herself, themselves, yourself, ourselves. since band members is a third person plural, the correct intensive pronoun would be themselves. if the band was talked about as a collective noun, itself would be the appropriate intensive pronoun. intensive pronouns are used to add emphasis to the noun it's modifying which is why it directly follows it.