We are going is definitely a correct translation here. Portuguese and English use gerund forms differently. In English, "Are you going?" Can be answered with "yes, we are going." In this case, no one is necessarily in the process of going. In Portuguese, "vocês vão?" Responded with "nós vamos" is the same meaning. Literal translations aren't always the best.
I think so. I'm a native American English speaker and we'd usually use "Yes, let's go" over "Yes, we go." In some places, "Yes, we go" might earn you weird looks or the thought that you can't speak right.
However, if someone asks: "Do you and your parents go to Hawaii every month?"
You can then say: "Yes, we go."
Is incorrect... we are going (in process of go to some place)("ing" continuous present), we go (we will go soon or when you accept an invitation for a party), im not native english speaker im native spanish speaker... But is common sense... i think...