Hi Kwee,
these are several questions, so I'll try to take care of them separately:
1) The Bookmarklet: you do not copy or paste that into Notebooks, you rather need to create a bookmark in Mobile Safari. This bookmark then is a shortcut for importing the document you are currently viewing in Safari into Notebooks.
2) Currently, you cannot put a note or sketch into a text note. - We had this type of functionality available in Notebooks 3.0 about a year ago, but Apple did not want to release that version and asked us to remove all "advanced" features again :-(
As a workaround, you can copy the link to a book or note (in Notebooks) and paste that into another note; this gives you a convenient shortcut.
(We are working on an alternative and hope to bring formatted text back to Notebooks soon!)