Hi
I learned a lot when starting with the 68000 by reading "Microprocess System Design - 68000 Hardware, Software and Interfacing" - by Alan Clements. PWS-KENT Publishing Company ISBN 0-534-98356-1
But I also learned a lot more by ordering an evaluation board with debugger, installing CodeWarrior special edition and stepping through code and writing new stuff. The manuals and instruction set references will fill in any gaps.
I would also go for the Coldfire rather than 68000. I think that the choice is much broader and tools are more readily available (not absolutely sure since I haven't used my 68302 and 68360 boards for years...).
For Coldfire peripherals "Coldfire Microprocessors and Microcontrollers" by Munir Bannoura, Rudan Bettelheim and Richard Soja is a decent overview, even if a bit expensive. In fact you may find a copy packed in with your evaluation board when you order it (maybe ask a Freescale rep. since they may have some in stock...;-)
Regards
Mark