Weekend update...not much to say, other than I had a pretty free weekend with no other obligations. On to pictures.
I finally lifted my rack into the A/V room opening and attached to the side studs. I thought I was going to need to put support underneath, but it is SOLID.

I bought some flat black spraypaint and painted the trim for my screenwash lights, smoke detector and riser step light trim. A few light coats and they turned out well.

I then moved on to painting. I put a second coat of black paint on the ceilings, and then moved on to the walls. I dont have a good picture of just the walls painted, but here is a picture of me beginning to mount the columns. Here you can see my permanent marker marks on the floor. I used these marks to help tell me where my studs were when attaching the second layer of drywall....that turned out to be a GREAT idea! I ended up using the marks again when mounting my columns. Here is a picture showing the floor mark transferred to the wall (just used a level).

Here is a picture showing my method of attaching the columns to the walls. The right marker line on the wall signifies where the stud is located, the left marker line shows the centerline of the column location. I marked the center of my 1x4 to line up with the column centerline and then used two screws to attach the 1x4 to the stud. I used a third screw on the opposite end of the 1x4 just for insurance - it only attached to the two layers of 5/8" drywall, but seemed to hold well if I didnt try to go too deep.

I used two 1x4's per column...

Then filled the column with insulation

Here is the column attached to the wall. To attach the columns, I predrilled a tiny hole and nailed a small finishing nail into the side of the 1x4. I also installed the light.

Here is a shot showing the sconce installed (with light off to see the actual sconce).

For the "what I would do differently" thread: Dont forget about trim when designing your theater room. I ran into a couple problems or almost problems.
Here is an almost problem. This picture shows the door and the column trim. That's right, the door clears the crown molding by 1/8" max! I think the door latch will just barely clear the side of the column also, so crisis averted.

That worked out okay, here I didnt get so lucky.

And the other side...these were different, as the stud layout changed slightly between sides (looking back, I should have installed the stud walls symmetrical...I didnt think it would matter). The tape is my 'clamp' to hold the tiny triangular piece while the glue sets.

And this is the final trim trouble...this wont be a huge problem, but I didnt have enough room between the door trim and the riser for a piece of vertical trim. I will install it and post a picture tonight or tomorrow when I get it finished. The blue tape is holding the return I have glued up.

Back to this picture for a moment. The unstained trim installed represents my inability to measure correctly. I minimized waste, but still ended up being about 24" short. The best news...I am out of dye! So, I need to order dye, have it shipped from New York before I can finish it up - mainly because the Woodsmith Store (where I got my first packet of dye) quit carrying the color I selected.

One additional thing to mention, I again used those permanent marker lines from the floor to help know where to attach the trim to the wall at. I would highly recommend marking stud locations...it saved me a lot of time. Plus, the studfinders (at least mine) has trouble locating studs through two layers of drywall.
I also need to build a threshold for the theater room door, so its not the end of the world. I also need to decide what color to use to trim around my equipment rack (white, black, or stained to match the door). Any recommendations are appreciated.
Also, just to note, after I finished painting the walls and before the columns were installed, I was worried about light. With my big work light and no column lights, it was pretty dim in there. Now that the column lights are installed, I dont even use the work light anymore. I suppose a dark carpet will pull a little more light out of the room, but I am pretty sure I will be okay.