interface for recording acoustic duo

hey,

I just formed an acoustic duo and want to record my acoustic guitar (plug directly into instrument channel and use condesor mic to pick up its natrual sound as well ), my vocal and my gig partner's. In that case, I need two intrument inputs and 4 mic channels(inputs). Question is what kind of interface suits me?

If I form a band in the future, so how can I plug in bass and drum?

Cheers!