Yes the data is fairly limited, on failure we get basic information with the TestCase/Test step that failed and a very brief error message.
We usually treat the JUnit report as an overview, and then refer to the console output for the details. To help navigating the console output we use the Log Parser Plugin in conjunction with making sure we write structured Ready API log file messages.
With regard to your question about paths, we have a Windows installation and we use a full absolute path, though I must admit I have never investigated using relative paths.