Modern home theater projectors are light and easy to install. Most manufacturers sell a mount to go with their projectors, though many other companies sell universal mounts that will do the same job (often for less money.
Most projectors are hung upside down from the ceiling, and a setting in the user menu flips the image so it's right-side up. The mounts are either near-flush with the ceiling or have a pole that allows the projector to align with the top of the screen.
Projectors all have different "throw distances," limiting placement depending on the size of the screen. It's important to map out where your projector *can* be mounted before you decide where you *want* it to be mounted.