As a former developer who has become a designer, there's a few things I'd suggest. First and foremost, start working on designs! If you have the ability, find a mentor who is already a UI/UX designer and start working with them on projects. I found I learned more by actually working on projects and absorbing knowledge from people who have been doing this for years than I ever did from reading a book.
That being said, if you do want to read up on UI/UX/etc., I'd take a look at this excellent thread:Must-read User Interface Book? I think my personal favourite is Steve Krug's "Don't Make Me Think" - but I'm sure you'll find your own favourite eventually.
Lastly, with respect to tools like Photoshop, Illustrator, etc... don't worry about it! Ultimately you'll find the tools that work best for you. Personally, I start with pencil and paper mockups, then depending on the project I'll either move to something in Balsamiq, or Axure, or sometimes straight HTML and CSS - it really depends on the project's size, scope, etc. Use whatever is most comfortable for you. At the end of the day all that matters is that you clearly communicate your vision for your design, not what tool you used to do it.