Language / Six questions about Polish Vocative Case [14]

Hello.

I have six questions about the vocative case, and I wonder if someone could help me. I don't speak Polish, but I am fascinated by it as a language and I'm enrolled in a class to start learning it in September.

1. I've read that both the nominative and vocative cases are used to address people directly. I would assume, then, that the nominative diminutive form of a name (like Krzyś) is also used to address someone directly – is this correct?

2. In what situations would someone be addressed by the vocative case, and in what situations would someone be addressed by the nominative case?

3. Is the vocative diminutive form of a name more affectionate than the ordinary vocative case? Would a close relative be more likely to use Krzysiu than Krzysztofie, for example?

4. What is the most affectionate way of all to address someone in Polish? Is the vocative case more affectionate than the nominative case?

5. What happens in the case of non-Polish names used in Poland (like, for example, Jewish names -- like Ester)? Are there rules governing the forming of vocative cases for non-Polish names, or would those names never have a vocative case? Would someone called Ester just always be addressed as Ester?

6. Finally, would you be kind enough to tell me the vocative case of the name Jakub, and the vocative case of the diminutive, Kubuś?

I'd be so grateful to anyone who can help me. Thank you very much for reading this.

Maria