So we are skipping a few steps. Main ones being: Framing an Windows. We do not do either, so we do not have much information for you about the topics. We can definitely recommend you to someone though!
So the next step that we can help with is electrical and plumbing! So you have the style of your home picked out, your blueprints, your contractor, Framing, Windows and Doors done. Next you need to get an electrician and plumber. (and HVAC, but we do not mess with that either)
At this point you need to have a good idea on your lighting. It does not have to picked out, but you need to know how many lights are going above the island, (and size) how many lights you want per switch, do you want stair lights, under counter lights, do you have a preference on where your light switches are?
You also need to choose which light switches you like. They are available in different colors and styles. You also need a good idea of your bathroom set up, so plumbing can work around your vanity, tub, and toliet choices. The placement for vanity lights will also need to be known.