OK so I remember seeing some screen shots before launch about ship customization and how we could change the saucer, the nacelles, the pylons and the primary hull. How do we do that?

Go to Earth Spacedock and visit the Shipyard. One of the vendors there ... he's to Matt Sissel's (or whatever his name is) right. When you go to him you'll get the option to "Customization Starship". Select it and then choose the Advanced Tab. You can swap out the Nacelles, Pylons, Engineering Hull, and Saucer from each of the ships that your rank will allow. Example: At Lieutenant you can swap parts in and out from the Miranda, Sharikahr, and Centaur. You also have the option of applying various astrologically-named skins to the parts.

Beware. It's pricey.

But the first one on every ship you get is free!

The Icon above the person is of a uniform top. There are two at Sol SB and I believe one at DS K7. There is not one at SB39. I have not gotten as far as DS9 but I suspect there is at least one there.