All of this information can be found on the PharmCAS website under their FAQ section. Since I'd have to go to the website to find it, i'll just let you do it instead.
Benefits of ED is that you'll know if you got in early in the process, allowing you ample time to get ready, but you can only apply to one school that way. If you don't get in, you'll still have to go through the regular process. Rolling admissions is nice if you apply early in the process because more spots are open; however, if you apply late, you'll be at a severe disadvantage.