One word: Gossip. Tell Richard as many bad things about Cassi as you can. This will address both of your problems. First, it will ensure that he doesn't become interested in her, and second, it will show that you really are looking out for his well being and that you are someone he can trust.
Oh wait..... Did you mean you were looking for good advise?! My bad!
Seriously, I agree with what the ladies have said. Prayer is always the way to go. As far as making the first move, that really depends on the guy. Myself, I'm not sure if I would have like it so much if my wife had made the first move, but then again I don't know - she is so great I probably wouldn't have been able to resist her! If Richard is the kind of guy that wouldn't mind it, go for it. But when you do, be careful not to lay all your feelings out on the line at one time. That would be a bit overwhelming. It is important to be direct and let him know your intentions, though. For one, it keeps the honesty in your friendship in tact, which is good even if nothing further develops. It also protects your emotions. If you don't let him know where you're coming from, there's a good chance he won't pick it up - trust me, I'm a guy, and we are pretty thick sometimes! If he doesn't pick it up, but you think he has, then you're going to feel led on if it ends up that he doesn't have the same feelings.
The most important thing is to leave it in God's hands. Either way, God has his perfect plan for your life (and it will be in His perfect time), and that is what you need to be seeking most of all.