Welcome to David (David Pardo Cossío) and many thanks indeed for your
substantial contribution (28.5.09)!

I'll just pick one point to comment on for now. You wrote that people are
"really cooperative when you make mistakes in grammar or vocabulary but not with
pronunciation." Yes - I suppose people tend to regard inappropriate intonation
not as a language mistake but as a matter of attitude or personality. And the
more accurately, overall, you can speak a language, the more dangerous it can be
to use intonation that turns out to be different from what's expected. So maybe
this supports the idea that intonation becomes particularly important at higher
levels?

Looking forward to hearing from other people.

Jonathan