I am going to make some assumptions. If going with an acoustically transparent screen with the depth of your room, you probably won't build a false wall and put speakers behind it. In walls would be a good choice and can have some acoustic advantages over freestanding speakers. An acoustically transparent screen is a good choice for better audio.

Since you don't have ambient light, I would suggest two screens based on the close viewing distance of your front row, so you don't see weave in the screen material.

Value: Seymour Screens with UF material
Splurge: Screen Excellence with NEO material

A 2.35:1 screen can have advantages in that you can get a larger screen for two rows and the 3 front speakers will be covered by the screen. You can't go too big with 16:9 screens because of sight lines and two rows. If at all possible I would try to keep the second row 2 feet from the back wall when reclined for better acoustics. Seating against walls is never ideal acoustically. That makes sight lines a little more difficult. There are tradeoffs in everything so I understand if it can't be done.

Using a 120" 16:9 screen as an example it is almost 60" in height (105" wide). If we have a 2.35:1 screen at 60" height it is almost 3 feet wider (138"). A lot more immersion and that projector will have no problem going between 16:9 and 2.35 with its lens memory. And, with your room conditions it will be bright enough. Since, this will be mostly for movies I think the 2.35 is a no brainer whether acoustically transparent or not. You will have black bars on the sides for 16:9 material.