I have done precisely what you are describing (projection screen that drops down in front of a flat panel in a living room) for the two years it too me to build my home theater room (I'm a slow DIY guy).
It is absolutely doable.
If your living room is light colored, has windows that leak a little light at night, and especially if you are going to keep a few small lights on when using the projector, a white screen is not ideal. But it can work.
You can pay a lot for screens, but there are decent choices that do what you want from Elite Screens or Silver Ticket that cost less than Stewart and Seymour (I have used both in my home) and SI (I've just seen screen samples and I like their Slate .8 gain material for your situation and I think it comes in a perforated version though depending on your viewing distance those perforations might be visible.)
Acoustic transparency means higher cost, few options, and sometimes less gain.
I know you can't rebuild your room but can you move your speakers to where they screen won't block them? That would give you more options for less money.
I would advise that you try to work with a dealer that will let you try the projector in your home for a day and return it if it isn't looking good. Some will, some won't, and some will have very specific requirements like you can only use ten hours on the bulb.
There is also NO SHAME in experimenting with screen sizes by getting a cheap manual pull down screen to try for a week. You can probably pick one up for under $150. This won't be a definitive test but can give you a sense of how it all works together before you make a hefty investment. Maybe you will realize you want a different size. Maybe you will realize you can adjust your speaker positions and don't need acoustic transparency.
Also, note that all the good screen manufacturers will send you samples of their screen materials. A few of the bargain brands like Elite (I think) will charge you around $5 per sample.
These samples, taped to that cheap screen you picked up for testing, can help you decide: Hey, is paying for ALR worth it? Is simple gray a good compromise? Do I like a white screen in this room? Etc.
In our living room we have extensive built-ins that limit the size of our tv to 55". Modifying the built-ins would be a massive undertaking so we are exploring other options. Our current thought is to keep our current Pioneer plasma and add a projector system to the living room. Typical viewing during the day would remain with the plasma and at night we would use the projector. For the projector I was thinking of something like the JVC NZ3 as it has a high lumen output that would allow for use other than just at night. We have curtains to control light but it is still a living room and open to the rest of the house. The projector will be about 13 feet from the screen.
The screen would be recessed into the ceiling with a motorized tab-tensioned screen (my ceiling joists do go the correct direction). The primary and farthest sitting position is 11 feet from the screen. I was thinking of a 106" to 110" acoustically transparent screen (my speakers will be behind the screen). I am aware that this is far from ideal and will be quite expensive ($3-4k), but is it crazy? One other thing, I will need about 42" of drop as my ceilings are 10' tall. My local home theater shop sells Draper and Stewart screens (along with JVC). I can expand my search to Knoxville or Asheville if another screen manufacturer is preferred as I am wanting to get this professionally installed.
I am open to suggestions and it is ok to tell me that this is not worth ~$8-10k I am thinking this is going to cost. Modifying the built-ins and installing a 77" OLED will likely be about the same cost. Thanks for your help.