Oh man, I'll try to help.
I would not call myself the 2.35 genius, but I do my best to make sure I understand.
It is very confusing and you want to make sure you figure everything right or it won't work. You'll want to make sure you figure your throw distance, screen size, etc.. correctly up front, or once you install everything it may not work when you add the anamorphic lens into the equation.
The nice thing about constant height 2.35 setups, like Skyhawk mentions, is that the height stays the same. 2.35 movies will fill the entire screen with no bars, 1.85 to 2.35 ratio DVD's will have black bars on the sides, HD material (1.78) will also have black bars on the sides, and standard 4:3 broadcasts will have the widest black bars on the sides.
Currently, when I watch say 1.85ratio DVD's, which is close to 16:9 I have the black bars on the sides and I am getting used to them, after a short time you really forget about them, just like bars on the top/bottom. However, at some point I may add black curtains to draw in for a better effect.
A 16:9 screen would require the least fiddling around, and if you don't mind a narrow black bar on top/bottom, that might be the best bet. You could always figure out a way to mask the top and bottom. Or some people adjust the projector so the top OR bottom black bar is off the screen, hidden by the masking border, and then just drop down a black velvet border to cover the top bar. There are so many options.
I know I'm rambling, and the wife is yelling at me to come to bed. ha ha
One thing is that you have to have something that will do the initial scaling or vertical stretch. The Panny S97S won't do it, I have one of them. The 900AU, I"m not sure, I know the new Sanyo Z4 will achieve this needed scaling. The other options, are a Home Theater PC, which I just got done building, or an expensive scaler like DVDO.
Basically how it works is when you watch a 2.35 movie on a 16:9 projector, you will have the normal black bars on top/bottom. Those black bars account for about 33% in lost screen realstate. Now your screen you build is 2.35 ratio, so at first you see the black bars on top/bottom as usual ,and the blank space on the sides, because your native 16:9 projector can't fill the 2.35 screen width, YET.
So, you first scale the image by vertically stretching it to reclaim those lost pixels on top and bottom. This also helps increase the brightness by about 20% because your using more of the panel for the image. Now everyone in the movie looks skinny, don't fear, now you introduce the anamorphic lens which stretches the image back out to fill the entire 2.35 screen and making the images normal looking. Confused yet?
Screen size, hmmm there is so much to think about here also. Ok so you say you are thinking about a 92" wide screen?
If you go with a 16:9 screen, then you would have the following: about 51.6" x 92" which is pretty big for 1.78 and 1.85 material. If you watched a 2.35 movie on this screen, it would be 39" high (92/2.35). 51.6" - 39" = 12.6" difference. Divide that by 2, and that is how thick the black bars would be on 2.35 material, about 6" each. Really it is about the same as when you watch a 1.85 movie on a standard 4:3 television.
I know I keep rambling, and not making any sense, it is hard for me to put this stuff in words.
Another thing to keep in mind is during a 1.85 DVD movie, you want to be about 1.3 0- 1.5 times the screen width back. So if we assume you build a 92" wide screen, that would be about 10 - 11.5ft back from the screen minimum. For 2.35 movies you want to be farther back as your eyes have to move from side to side further.
You will also want to make sure that your Panasonic will be able to achieve a 16: 9 image from whatever throw distance your planning. If you build the 2.35 screen, the projector will produce an approx. 16x9 image of 39" x 69" so your black side bars will be about 11.5" wide on each side.
Here is the calculator for your projector, it appears between 8' and 16' you can get that screen size for 16:9 images, you just don't want to have you zoom maxed out to achieve it...
Its late, and I'm sorry for rambling, I've had a few cold ones and know I haven't answered any of your questions, and probably confused you more.
Heck, just go get a sheet of 4ft x 8ft Parkland Durotherm Lite panels from your local home improvement store, trim it to 16:9, hang and enjoy, no painting required. Heck, I have a gallon of MMud in my closet never opened I should have sent you.
good night, burp....
PS: most DVD's are either 1.85 or 2.35, about 50% in my collection, if you read the back.