For a two family I would use a 2 gang meter socket. One 200 amp riser from that, a hundred amp feeder to each panel. I see no need for a gutter at all. This is all the info I can give as this is NOT a do it yourself project and while it is good to see you trying to learn, this board and some books are not going to make you an electrician. If I lived in that duplex I would not be happy to know the wiring is being done by some handymen. In fact I would notify the local authorities.
