If you're at a University that subscribes to the Springer library, you can download the book for free from the Springer Link. A version of the text with internal links and updated for use with astsa can be found here: tsa3.
An easier version of the text is now available (for free). This was accomplished by removing Chapters 5, 6 and 7, and some sections in the other chapters and reworking some of the stories and exercises. You can download it here: tsa3EZ. The preface has more details on how this magic was performed and how to work the machine.
A text on Nonlinear Time Series Analysis was published by Chapman-Hall in January 2014. The text can be used as a second course in time series analysis.
To download R, go to CRAN and choose a mirror close to you. The installation includes help files and some user manuals. You can find helpful tutorials by following CRAN's link to Contributed Documentation.
The R issues for time series analysis page is still alive because, while everything changes, some things stay the same.
The html version of the R time series tutorial has been updated for edition 3. Go here to get your Quick Fix.