I found a designer on Dribbble by just emailing them with a brief explanation of what I need, what my budget was and asked if they were interested. Make sure you only ask people who's work you actually like and you shouldn't have any problems.
The Pragmatic Programmers book on Rails is very good and already updated for Rails 4. If you get through it and still want more, the Rails Way is the most comprehensive book I've seen. Railscasts is great once you are making apps on your own as it tackles small specific problems.
Don't forget about the official Rails guides themselves, they are actually quite helpful.
I go back and forth on whether learning Ruby first is best. You will learn more about Ruby itself just by solving RoR problems, but I think you would solve them faster if you already had a solid base in Ruby.
I don't have experience in ebooks but I did just release a free album and I think there may be some crossover. Here's some stuff that worked for me:
1. Make sure it as easy as possible to access your work. Even though it is free, you are still asking a lot from your readers by asking them to pick your content over all the other content out there. For example I made a built-in player for the website and a one-click download link.
2. Send a brief email to people you respect within the community. This could be bloggers, other writers, forum posters. For the last year I collected a list of websites that I liked and when the album was done I had a nice list of people to contact.
3. Accept donations! I was surprised by how many people wanted to give me money. There's nothing wrong with this if you don't be a jerk about it.
I guess this is mostly pretty obvious, and there's no substitute for having good content!