get or post

[john abhraham]

Hi all,
i got a bit confused on the questions on page 19 of hfsj.
Should i use get or post in the following situation (on what basis?)

1. A user hits the next button to see the next page.
2. A user hits the logout button on a secure banking site.
3.A user hits the back button on the browser.
4.A user makes a radio button selection.

As there are no answers for these, i am a bit confused.

Regards,
John