Couple of very easy photoshop questions

Hello, i’m kind of new to photoshop and i have some questions and if someone could give me an answer it would be realy helpfull:

  1. How to i break an image in two, but not following a line, but more like a courve, much like breaking an image in two pieces of a puzzle. Please, if you can, walk me step by step through this, 'couse well… i don’t quite understand photoshop :))
  2. How can i make use of those custom shapes found under the custom shape tool. I want to color one with a specific gradient or that sort of thing and i can’t figure out how.

Thank you and best of luck.