Hi OldMan,
At a minimum you need a BDM pod, to convert USB to BDM, a piece of hardware.
See P&E Micro's USB-ML-12.
Then you can download Codewarrior 5.1 for free from here. (Assembler/Compiler/debugger etc)
The DEMO908GB60 is out of production AFAIK.
You may be better off (cheaper) with a QG demo board as it includes the BDM pod on board and total cost is half of a pod. (Or an AW one, see other current thread here.)
There is no clear answer to this. Does minimum mean minimum money? Codewarrior may cost you as its a huge download.
Anyway some ideas for you.
Regards
Peg