Does Confluence have protection against spam bots?

Yes. To protect against spam-bots, Captcha can be turned on for editing pages and for creating comments (or requesting an account, not relevant for us).

To avoid impact on legitimate users, Captcha has possible (global) exclusions: No-one / Signed-in / Members of a group. Signed-in is the default and is what we are using at this wiki. Signed in users are exempted from Captcha, and so only anonymous users have to go through Captcha. It is then still up to each space's admin to decide whether anonymous users are allowed to edit pages or to comment.

Can I get notified when someone edits a page – or edits any page in a space?

Yes. One can "watch" a page or a whole space, and receive email notifications when someone creates or edits a page:

To watch a space:

Browse -> Advanced -> Start watching this space

To watch a page:

Tools -> Watch

How can I paste in entire documents - pdf, word, ODF?

Confluence can import a word document into the wiki markup. Choose the Doc Import command from the Tools menu.

Can Confluence export or print a whole hierarchy of pages?

Even though Confluence cannot do that directly, you can include the Child pages in the parent page, so that their contents is display inside the contents of the parent page.

Use the include macro in your parent page at the place where the child page should be rendered:
.bq