When you’re davening Maariv, do you say the end of the blessings (Blessed are You, L-rd, who brings on evenings and Blessed are you, L-rd, who loves his nation Israel) yourself, or can you rely on the chazzan and answer Amen? Can you do both, or would it appear as though you were answering Amen to your own blessing, which would constitute a forbidden interruption?
Also, are you allowed to say the blessings and the 3 paragraphs of the Shema (except the possuk rishon) in a quiet voice like the silent Amidah?