You could take a page from the same place as Java, Ruby, Objective C, and others and check out Design Priciples Behind Smalltalk. Much of this is foundational material on communication between objects, rather than anything about Smalltalk specifically.
As far as really thoughtful books on langauge design, I think The Design and Evolution of C++ definitely deserves a mention. I hesitate since you say that you want the "perfect" OO language, and C++ is far from perfect. You could probably still learn a lot from it, though.
The points you bring up, though, seem like they have more to do with the Principle of Least Astonishment or the Rule of Least Surprise than with the design of language internals.