I agree with you on most of that. Here's my advice on learning to program...
Despite what many people say, Basic is still a very good language to start with, and most Basic languages behave the same for simple stuff like string handling. The main gripe that people have with AmigaBasic is that it isn't very compatible. A better solution is to look around and find a small freeware Basic (there are plenty around). This should be compatible with AmigaBasic, and with your system!
Once you can program well in any Basic, you can then move onto something like C. My advice is NOT to use somehing like AMOS. It was great when it was new, but really shows its age now. The advantage to AMOS was the ability to make nice effects using lots of high level commands. AMOS doesn't even support AGA!