If you're coming from Java, I recommend the Scala for Java Refugees[1] series of blog posts. If you're interested more in the functional side, there is a course by Odersky on Coursera right now.

I haven't found any Scala IDEs stable or enjoyable yet. I've been using [insert favorite editor] with sbt[2].

[1] http://www.codecommit.com/blog/scala/roundup-scala-for-java-...

[2] https://github.com/harrah/xsbt/wiki