If Freescale/NXP will not support old legacy versions of Codewarrior, what version(s) do they support?
Freescale use to be quite generous just to get you to use their devices. I worked on a project where they gave us the MQX RTOS free of charge.
Will they give you a free upgrade to the current supported version?
Very few microcontroller tool chains are available for Linux, let alone supported.
Almost all comercial companies that do microcontroller development will be Windows based, so there is little for the microcontroller companies to gain by developing and supporting Linux development tools.
From what I can gather, hobbiests and Linux fans have cobbled together ARM development tool chain of some kind. Just like Linux based things, it is all command line based and really involved to get it working! Being a commercial, professional embedded systems developer, you can take those Linux tools and keep them. The commercial tools usual work and are easy to use, leaving you to get on with development and NOT trying to get the toolchain to work