I just finished Rivet City, too. What I did was went to the old man under the boat and got the proof Moira needed. I also got the password to the android to access his old info of what he was and said it to him. I then told him he can trust me with his secret and he gave me his awesome laster rifle. I can sell it for 2,100 caps! Then I sold him out anyway, to Dr. Zimmer and got my reward from him too!
I also got that chick and Diego married, and went to the ceremony, only Diego didn't show, so I filled him for him. I got good karma and a great way of assembling a lot of the 'town's folk' in one location at the same time! All it cost me was some ant pheromones.
Oh, and RC has no items at all. Only merchants. Want free stuff? Go to the CEO building. I've made four trips of premo stuff!
EDIT: Also, I bought a second schematic, and it didn't raise the DAMAGE value of my weapon any. I guess I had to make second weapon and "repair" it, or not? So, I reloaded the save and then didn't purchase it again.