In re: comments, I've found that any time I would write a comment, I try and see if I could re-write the code to make the comment redundant. It is possible to do this in a surprisingly large number of cases.
As for #5, practice makes permanent. Writing lots of poorly thought out code just ingrains bad habits.
Sure self explanatory code is the goal. But in the real world this is never entirely possible. File parsing for example. Without seeing the file being parsed it can be very hard to interpret the code parsing it. Or maybe you are interacting with other software that doesn't always respond predictably to your code and you need to explain why these calls are made in this order.
I agree that practicing bad habits is unhelpful, but I still maintain that the best way to get better at programming is to program, particularly by writing and contributing to open source projects in your spare time.
As for #5, practice makes permanent. Writing lots of poorly thought out code just ingrains bad habits.