I think the reason you haven't had any replies to this thread is perhaps your room dimensions are restrictive, long and narrow. But I think you could definitely do something with that space if you are prepared to compromise.
SCREEN
You may just squeeze a 90 inch diagonal screen in the room with a 2.18 meter width but definitely an 80 inch. careful measurements will be required to make sure the case (including connections which may be on one end) can be accommodated. So this is your starting point I would think.
Next your screen will need to be acoustically transparent so you can put speakers behind it. You have no space for speakers either side of the screen so this is the next important consideration. personally I would investigate the screen first before going further with the project. If you can find a good 80" screen that fits the bill you at least know the project is possible.
There are screens that can be ceiling or wall mounted using brackets which you fix to the wall or ceiling then hook the screen on afterwards. In your case and assuming you have that jutting wall section on each side of the room, you would fix your brackets to the wall near the ceiling. Have a look at Eyeline Pro screens to get an idea of the brackets fixing method I am talking about.
Many here will say that a tab tensioned screen is a must and certainly on larger screens and pull down screens which tend to get a lot of strain in the middle where they are pulled, they sag over time which looks hideous and ruins the image completely. A small electric screen on the other hand maybe isn't as prone to issues and certainly some have screens that are non tab tensioned without any problems. Its a risk that you will have to weight up. For real peace of mind tab tensioned is a good idea but if budget is limited........
PROJECTOR
In your narrow room your restricted screen width will mean you have limited options regarding your projector position. Ceiling mount is better in my opinion. BenQ manufacture some inexpensive DLP projectors which are popular on this forum and I am pleased with the W1400 that I very recently installed. It has reasonable blacks, not spectacular or even very good but absolutely OK considering the cost of the unit. All of the BenQ range including the W1070, W1080, W1300, W1400 & W1500 have very good colour, nice bright images and very good 3D. I think for the money the BenQ projectors are well worth consideration.
Optoma and Epsom also produce competing products worth investigating. It really comes down to the throw ration of the projector in your room, what you use it for, lag for example being a potential issue with some BenQ models if you use it for online Gaming and of course how much you want to spend.
BenQ have a calculator for working out where to mount your projector and this site
http://www.draperinc.com/projectionscreens/ProjectionCalculator.asp also have a useful calculator for other projectors you may consider.
For mounting the projector you would need a good bracket and there are plenty available, some are terrible, some are good, others are excellent. What is essential though in any universal mount in my opinion is that it is strong, has adjustable height and preferably adjustment for Roll, Pitch and Yaw. Search the threads for mounts and have a look at Amazon customer reviews too. There is nothing more useful than opinion by existing owners and customers in gauging a product in my opinion.
COLOUR:
One thing that is important is the use of colour on walls and ceilings to minimise reflected light ruining the image contrast. Darker colours are better so forget pale crème, beige or similar colours all of which are far too light. Dark colours help to control the light in the room and make for a better image. Because my HT is also a room for other purposes I painted the walls and ceiling a mid blue colour which is OK but for a dedicated theatre you can use even darker colours. Have a look at the Home Theatre thread for ideas.
That is about as much as I can offer in terms of advice having set up a very modest HT in my own restricted room size of 2.6M Wide by 3M long which is by no means a large space. Hopefully others will chime in and help too. There are good helpful people on this forum with a wealth of experience and knowledge which exceeds mine by a massive margin who I am sure can answer any questions you may have. But hopefully my pointers based upon my experience setting up my HT will at least point you in the right direction.
