Headscratchers / The Gallows

• If Charlie died as a teenager, then why does his ghost have the body of a grown adult?
• Pfeiffer's whole existence is a plot hole. First, when did Charlie and Alexis have her? Did they have her in school? Second, Charlie died in 1993, and the movie is set (presumably) in 2015. So this would make Pfeiffer around 21, yet she's still in high school. Was she held back a few years?