Re: Need advice on new cats
Other people will be much better resources about the introduction process than I am - we did ours "all wrong" (isolated Othello for the first day, until we could get him to the vet to check on an upper respiratory infection, then just let them both out together with no formal introduction beyond the paws-under-door they'd been doing). There were several weeks of squabbles, hissing, and chasing sessions that usually ended with Desdemona cowering under the futon. One thing that really helped us was a Feliway diffuser - we left one of those plugged in for three months or so, and I think it did help them both calm down with each other. Not cheap, but worth it. You might try that to see if it can help Joy calm down in her room. (Does she have everything she needs in that room - food, water, litter box, scratching post, toys, someplace to hide? Do you keep her company and play with her/pet her in her room?)
One other thing that was recommended in the "Cat vs. Cat" book we picked up is using play to help build confidence in a scaredy-cat. Some good interactive hunting sessions with a toy like DaBird can help them feel more like a predator, and therefore more confident in their dealings with the other cat. Desdemona used to be a total scaredy-cat, but she has come a long way in the ten months we've had her. It can also help an aggressive cat burn off some of that energy so it doesn't all get directed at the other cat. Might be worth a shot for your two. Joy is still pretty kittenish at 8 months, and probably needs a whole lot of play time for all that energy!
I hope some of that is helpful - good luck with your new furry little ones!