Literal translation would be "We are coming in a little" This a common phrase in English and should be accepted as well.
It's incorrect. I don't know if that answer had been included in the alternatives some time ago, but it's not in the alternative translations any more.
"We come" is the habitual present, denoting a repeated or regular action. That doesn't make sense with "soon". So the English sentence must use the continuous present. Here we're using it for the case of a one-off action that is about to start: http://www.bbc.co.uk/worldservice/learningenglish/flatmates/episode73/languagepoint.shtml