I want to start a niche publication of my own and researching the business model of Readers Digest?

I am particularly interested in the legalities involved in identifying content in other magazines and reusing them in my publication after editing/condensing.



Should I get permission from them? Should I pay them? Should I share profits with them? How did Readers' Digest do all this? Are there any case studies that will provide details?



Thanks in advance for your help.