What home theater projector should I buy?

I am looking at putting in a home theater. I think I have the seating covered. It will be in a dark room, and I want to buy a projector (they seem to be the best quality for the buck). I don’t really know anything about them. Do I need a screen? How big (I’ll be about 12 feet away)? What type of projector should I get? How can I know how good of quality a projector is? What is the display technology mean? What is the contrast ratio? What does the brightness mean (Lumens?)?

Thanks a lot, I really appreciate it!

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