Acoustic Panel Mounting Questions

I've had Corner Tunes (from Room Tunes) in place for years and want to add a Bass Trap for behind my listening position, as well as Ceiling and Side Wall panels to absorb first order reflections. I peeked inside one of the corner tunes and it is simply 2" thick insulation that is aluminum faced on one side enclosed in muslin. I intend to use this same approach in fabricating my new traps, buying 4" thick insulation for the bass trap and 2" thick insulation for the other panels. I've read that the bass trap should ideally be mounted a couple inches off the wall and with the reflective material facing outward. Should the ceiling & side wall panels be mounted the same way - off the wall/ceiling and with the reflective side facing outward? And how large an area should each panel cover - would 24"x 36" be adequate? Does it matter at what heighth the panels are mounted on the side wall?
Thanks in advance!