Thanks Tim. I will try HVAC talk and see if I can find someone locally. I was able to meet with a "friend of a friend" last night who is a technician for commercial HVAC controllers and sensors. He doesn't do residential HVAC work, but he was happy to look at my project and give me some suggestions.
The first thing he told me was based on the level of complexity of the existing system I have installed combined with the fact that I have a pretty precise plan of what I want, this isn't going to be a 2-3 hour job for someone and my plan of having someone come in to "finish it up" for me probably won't be as cheap as I am thinking. He said I had done a good job with what I have already done and suggested hiring someone to run the numbers and develop a plan and then install it myself to save some money. Depending on the quotes I get, I may go this route.
While he didn't take any measurements of the existing system, he did have some software that calculated air requirements and duct size based on a bunch of parameters. He emphasized that while it is important not to under size the system, it is just as important to not oversize it either. He said if My ducts are too big, they could be loud and the room may feel drafty. He wasn't familiar with home theater equipment, but he has done work with computer rooms and he recognized that even a small amount of equipment can heat up the room fast. He said that as a rule of thumb, you want to exchange the air in a computer room a minimum of 10 times per hour. He wasn't sure that this would be necessary for a theater, but his point was that proper HVAC design would improve the experience in the room.
He asked if it would be possible to put a temperature controlled exhaust fan in the equipment closet. I told him I would need to find out more about it, but I knew that people on AVS have done that. He thought that would help significantly.
He also looked at my plan for running two supply ducts in and looked at the issue with the joists not lining up. I had calculated that I could fit two 10x6 rectangular ducts into the theater to maximize the amount of air flow into the room. He pointed out that a 10x6 duct is not a standard size and I would have to have them made which could be costly. He said that this was the equivalent of an 8.4" round duct and suggested just sticking with an 8" round which is available at most stores. He felt that if I could even exhaust some of the heat from the rack, 2 8" ducts would be fine for the room.
Lastly, he suggested putting linear diffusers in the center of the ceiling to reduce the number of bends/turns in the ducts. He said if I try to run them into the soffits it may restrict the air flow more if I'm not careful. He said if I paint the diffusers to match the ceiling, they won't be "obvious" and will blend in well.
I feel better about the direction I am heading. I need to get someone to confirm my plan by measuring actual air flow of my system and then create a materials list. Hopefully I can get someone out in the next week and order what I need so I can finish this up. I am getting pretty anxious to get past this milestone.