Hi Walkero,
As iamaboringperson said, the developer pack should be released soon after OS4 is released. At least, I would be surprised if this were not the case.
The best books for Amiga programming were the Amiga ROM Kernal Manuals, but unfortunately they are now difficult to come by, though not impossible if you are patient. They also focus on Workbench 2, but are still largely relevant. Using this and the Release 3.x release notes/autodocs, you should have no real problems making programs for later AmigaOS versions. Until then, if you obtain the Developer CD 2.1, you will get AmigaGuide versions that you can view on your Amiga. Nothing beats an actual book, though, IMHO.
There are sites to help in programming the Amiga and installing gcc. I cannot remember them offhand. I will post them later if no-one else beats me to it, but they probably will.
