What is the difference between a sliding and a non-sliding miter saw?

The sliding rails let the head travel forward, so the saw crosscuts wider stock than a fixed 12-inch saw of the same blade size. The trade-off is extra depth behind the saw and more weight.

Can it cut wide boards like 2x12s?

The sliding action is what makes wide crosscuts possible on a 12-inch saw. Check the board width against the saw's stated crosscut capacity before buying for a specific job.

Does it bevel as well as miter?

Yes. It is a compound saw, so the head tilts for bevel cuts as well as rotating on the table for miter cuts. That covers crown molding and angled joints.

Does it need a special outlet?

It runs on standard AC mains power. A 15-amp household circuit is typical for a saw of this size, but check the motor's rating on the label.

Is it good for a beginner?

It covers the common cuts a beginner needs, and the controls are straightforward. The main adjustment is learning to allow for the sliding head and keeping the workpiece clamped.