Here is a list of questions that are often asked by new visitors to these forums that may already have excellent answers elsewhere.

First though: If you are new to the forums, and your answer is not detailed below, please make sure to use the search function located in the upper right corner of your screen in the light brown box. It says 'SEARCH' and can help you get some answers that may have already been covered. Also be sure to look through https://www.projectorcentral.com for reviews, articles, and general excellent information before asking a question.

Official FAQ List (answers begin after list)
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1. What is the best projector for viewing DVDs and HDTV?
2. What is the difference between a business and home theater projector?
3. Why is projector 'x' listed as the best on Projector Central?
4. What size screen should I get?
5. Where do I mount my projector?
6. Which is better LCD or DLP or SXRD/LCoS?
7. What is lens shift & do I need it?
8. What wiring do I need to run for my projector?
9. What other expenses do I need to consider with my projector?
10. How should my room be setup?
11. What does the difference in resolutions mean? 480i? 480p? 720p? 1080i/p?

Answers:
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1. What is the best projector for viewing DVDs and HDTV?

A: The best projector is always highly dependent on the room it is going into, the equipment that will be used with it, and the budget available. Generally speaking, for home theater use, any projectors on the 'Highly Rated Home Theater Projectors' list is a good choice.
https://www.projectorcentral.com/home-theater-projectors.htm
Yes, there are many choices, and the really good news is that there are lots of excellent choices for your money. A good recommendation is to get a high definition projector with at least 720p resolution.

2. What is the difference between a business and home theater projector?

A: There are many differences specifically related to what a business projector is expected to do vs. a home theater projector. Mostly it revolves around the need for a home theater projector to accurately display video on your screen as true to life as it can, while a business projector is designed to show PowerPoint presentations in a board room. Not nearly the same requirements at all.
Until Projector Central adds something similar, here is a list of differences to consider:
Differences Between Business & Home Theater Projectors

6. Which is better LCD or DLP or SXRD/LCoS?

A: DLP has for years had an advantage over LCD in this department - This is no longer the case. Anyone who simply says that DLP is better is not properly educated on the quality of current LCD projectors. It is important to judge each and every projector individually based on its strengths and weaknesses. An excellent primer is here:
http://www.projectorcentral.com/lcd_dlp_update6.htm

Sony and JVC offer another option called LCoS (SXRD by Sony) which offers excellent performance as well and should be strongly considered in a quality theater installation for use.

7. What is lens shift & do I need it?

A: A zoom lens on a projector lets you move the projector closer and further away from the screen, lens shift on a projector allows you to move the projector up and down, and possibly side to side, in relation to the screen. This can be of a great benefit to those who have low ceilings and want the projector ceiling mounted, or for those who have high ceilings and want to use the same projector for ceiling mounting. It is an excellent feature, but the range of motion for lens shift varies depending on the projector you get. The owners manual for any projector should be reviewed prior to purchase if this feature is important to you so you can determine the range of lens shift available to you.

8. What wiring do I need to run for my projector?

A: If you have easy access to run wires whenever you want to your projector because you have a drop ceiling, or are running wires on the wall, then you only need to run wires that you need. But, if you have a drywalled room and the wires are going to be permanently mounted, then you should run all the main wires you need the first time. Bonus points for leaving access to run wires later!
Minimum run:
1 HDMI Cable
2-4 Cat-5 (or Cat-6) Cables - Cat-X cabling can be used for a number of different purposes and helps to 'future-proof' your system.
1 120V A/C Power Connection To Plug The Projector Into

Bonus:
1 inch Flexible conduit so you can run extra wires through it later
1 component video cable
1 composite video cable
1 SVGA (or VGA) cable so you can hook your computer up - Do NOT plan on being able to use something other than a SVGA/VGA cable for your computer connection, though HDMI may work as well. Some computers have composite or s-video connectivity - this is FAR worse quality than SVGA/VGA cables and should be avoided. HDMI or DVI on some laptops is excellent and can often be used, but many laptops only have SVGA/VGA 15-pin connectors on them.
1 S-Video cable

9. What other expenses do I need to consider with my projector?

A: A projector is just a video display device, like your computer monitor. It rarely includes speakers, and when it does, the speakers are usually of low quality. So, the number one expense you will have with your projector is an audio setup. Audio systems can be as simple as a pair of computer speakers for well under $100.00 to well over $20,000 for a full blown setup. A good plan is to spend about as much on your audio as you do on the projector, though decent systems can be had starting about $700.00
The next most expensive item is typically your screen which can be from about $100.00 to near $4,000.00 depending on the make/model.
Additoinal expenses are your sources such as DVD player, HD cable/satellite, DVR, VCR, gaming systems. The setup options for all this equipment is endless.
Finally, you will need wiring between individual pieces of equipment and the projector and speakers, etc. Wiring can be very expensive and not give you any extra benefit, so care should be taken to not be suckered in by companies that charge you more money, but don't deliver a better product for your money.