My thoughts on all of this:
If you own this place, then do it right. Don't talk about wire management like exposed wires are acceptable. They really shouldn't be considered as such, and if it is your home, doing it with hidden wires is the best way to do things.
There are 3 main things that have nothing to do with the projector which would really make this setup 'pop' IMO.
1. Add recessed lights to the ceiling on a dimmer. Putting in recessed lights means you cut holes in your ceiling to put those lights in. Those holes give you access to run video and power cabling to the projector ceiling location. Doing proper in-ceiling lighting also allows for more zoned control of lighting in the space, and gives you better value to your home. It's a fair bit of work, but not really that difficult to accomplish.
2. Figure out all your A/V wiring and get it taken care of. This is the most time consuming part of your setup. Hanging a screen and a projector is easy. Taking care of wiring is not. There are tons of videos online about running wires, but for the most part, I think it starts by looking in any parts of the basement which may be unfinished. Look for pathways behind walls, and across ceiling joists. Sometimes the best path is not the most direct. Sometimes it is. So, look for ways to run wires, and consider #1
(above) as a way to create pathways that don't need to be 'fixed' when things are done. A lot of planning goes a long way. Remember, your equipment should NOT be at the front of the room! Put it in an unfinished space, or way off to the side. Build it into a wall, whatever - but little LEDs blinking at you while you watch a movie aren't part of the theater experience.
3. Your room color sucks. As shown in the photos from the previous post, light bleeding onto walls and ceilings and equipment right below is very distracting to the experience. I mean, it's an awesome big screen setup, but the single biggest improvement anyone can make to a home theater setup is $50 in paint. You have a nice break point with the ceiling which would allow it to be painted dark, and you can go with any number of paint schemes to the walls to separate them out and make them darker. Dark browns towards the screen area, lighter browns towards the back of the room. You really want to create a 'space' which the theater exists within, even if it isn't a dedicated room.
Now, into equipment...
The BenQ W1070 remains a great option. Around $750 and minimal offset, allow it to be placed such that it only needs to be a couple inches above the top of the screen. That's ideal in your setup as the projector may need to hang from the higher part of the ceiling and have the lens just under the lower part of the ceiling. This gives you the most flexibility in placement of the screen.
I would stick with a mount that allows you to use 1.5" pipe, or build a mount yourself that allows for this. You want your projector to be as tight as possible in location. Read this thread: My DIY mount for L300u $20 :)
- That mount idea lets you control all aspects of the projector leveling (important) while keeping things inexpensive.
Screen - FIXED FRAME! - Manual screens are garbage overall. They often have waves in the material right out of the box. So, get a fixed frame screen. There are a lot of options out there. I would recommend the Elite Screens - Sable series. But, there are other choices that may be better suited to you up there. Likewise, if you are willing to put in the effort, you can build your own screen for a good deal less out of pocket expense. IMO, building a screen just isn't worth the time and effort considering the cost of the cheap entry level options. But, it's your time and money, not mine.
For cabling, check Amazon, but if you are putting in the effort to run wires behind drywall to the projector location, make sure you pull AT LEAST: 1 good HDMI cable, 3-4 cat-5e or (preferably) cat-6 cables. Use raw, unterminated cat cabling. It would be better to run conduit, but this is very unlikely to be able to do. If you find, that your wire paths allow you to add/remove wire at any point, pretty easily, then just run a single, high quality, HDMI cable to the projector. Redmere cables are a good choice if you can add/remove them later on easily.
For audio, there are a number of options, and it's worth having a completely separate discussion about. Figure out a budget, then go from there. But, if you have no audio, then Accessories4Less is a good starting point to look at. Specifically, they have pre-packaged home theater in a box kits that are of decent entry level quality for next to nothing.
For example, this setup uses a proper A/V receiver with 5.1 speaker setup and 4 HDMI inputs. You may need to do some figuring with these guys or go elsewhere due to shipping policies, but there are definitely solutions.