Oliver Peter’s at Digital Films has a great article (among a huge, and equally great, back catalogue) on working with Arri Alexa footage in a variety of NLE’s.
Useful free downloads include:
Log C to Rec 709 fcp plugin from Antler Post (Watermarked demo is free, $30 full version)
Arri Digital’s web based LUT generator – A variety of free LUTs for different scenarios.
Red Giant’s LUT Buddy – A free plugin for several NLE’s to create and read LUTs.