Go to the travel nure specialty section, there are several threads in that part of the site that will answer your questions.
Travel nursing is what you make of it. If you are looking to experience new places then it is a great opportunity to get out there and see the world. If you are looking for pay however it might not be what you expect if you are from one of the already high paying states such as CA.
There are several travel companies...TONS. You really just have to go out there and research and see which one is the best fit for you. You will see mixed reviews for a lot of companies but you really have to focus on what YOU want and need from a company.
I have been traveling for 2 years now and there are things I love about it like traveling to different cities, meeting new people, and experiencing a different aspects of nursing; but, there are also some things I don't enjoy such as being away from family and having to up root my life every few months but the good outweight the bad for me so I am continuing on this journey for now.