I reply to myself, adding some things I've found.
From what I've seen so far, the native search in the "Documents" area doesn't work properly (result is always zero, even when I use the title of a page as the key), nor it's allowed to assign tags to pages.
So, a workaround for my purposes could be using the "suitcase" area, where on the contrary it's possible to assign tags to document.
Anyway, I'd rather being able to use "documents" and "tags" (and search) together... |