Writing in passive voice is not wrong, it is simply not usually the prefered form of writing. Reasons are:
(a) it is not direct,
(b) it is usually wordy and redundant,
(c) it is not as clear nor as positive as active voice.
Follow your teacher's instructions on this. Usually...
Compose and comprise are synonyms, both being verbs forms, meaning consisting of. Being present tense, as represented by the word
are, the "ing" needs to be added in the example sentence. Comprising is the favored word, since composing often refers to words, rather than to people.