Does PE10 support image masks? It's a useful feature in AE, where any shape mask may be created in Photoshop then imported and applied as required.
Welcome to the forum.
Yes, PrE supports masks, and most often in the Track Matte Keying Effect, where your mask/matte acts as a "window" to limit a Video Track/Clip.
To get a little bit of an idea of how thise works, you might want to look over this ARTICLE.
PrE is an NLE (Non Linear Editor), like Premiere Pro, so there are some major differences between it (and also PrPro), and After Effects, which is a compositing/animation program. Some similarities, but also some differences.
What exactly is it, that you want to accomplish, and we will try to tell you how well PrE will handle that. While powerful, for many operations, it is no substitute for After Effects.