Lopez isn't a project. He's too old to be a project at this point (NBA players usually reach their potential by 24). He is who he is.
With that said, he's certainly capable of being a backup center. Although personally I think he has a legit shot at being the spot starter on this team with Ryan Anderson being the sixth man but seeing the floor a lot more often. Lopez could start, but likely would only average 12-20 minutes per game.
As for best lineup... it will probably be:
Rivers (assuming he develops quick enough, but I don't think he starts any time soon)
Gordon
Aminu (for defense)
Anderson
Davis