• Select the note to Explode
• Note menu -> Explode.
  
  • Before you ask, there is not automated way to invoke Explode via either a shortcut or action code.
• On the Explode dialog, set the desired choices (if not already the defaults).
• Click 'Explode' button.
• Use TB action code to set the back-links to source (insufficient info as yet to given a more detailed answer).

• Hack the script Listing (which is included in DT) to include the text of each selected document, its DTP-link and its tags. (By default it only provides a list of the titles of all documents in the database.)
• Include distinctive markers at the beginning of each DTP document, and round each DTP-link and its tags, so TBX can work on them later.
• Run the script on the documents you want to export, and save the result text file, which looked something like this:
  
  Code:

  @@@ <A>First Document name </A>
  <tg>Tag1;Tag2;Tag3</tg>
  <ln>/x-devonthink-item://EF28548A-C596-461D-BA19-D37A80F077C5</ln>
  This is the text of the first document
  
  @@@ <A>Second Document name </A>
  <tg>Tag1;Tag2;Tag3</tg>
  <ln>/x-devonthink-item://etc</ln>
  This is the text of the second document 
  
  

• Import this document into TBX. Explode it using @@@ as the delimiter.
• Run agents on the exploded documents to strip out the tags and the dtp-link and put them into attributes within each new note. E.g. in the Agent Query field, use
  Code:

  Text((<tg>)(.+)(</tg>)) 
  
  

  
  
  And in the Agent Action field use
  Code:

  Tags = $2 
  
  

  
  (This procedure is described in the TBX menu.)
• Eventually you end up with a single note per DTP document, including the content in the note body and the tags and link added automatically into the relevant attributes.

set dataString to "Name\tURL\n"

tell application "DEVONthink Pro"
   set itemList to selection of front window
   tell front window
	repeat with anItem in itemList
	   set itemName to ""
	   set itemLink to ""
	   set itemName to name of anItem
	   set itemLink to reference URL of anItem
	   set dataString to dataString & itemName & "\t" & itemLink & "\n"
	  
	end repeat
   end tell
  
end tell
tell application "Finder"
   set the clipboard to dataString as Unicode text
end tell 

set dataString to "Name\tURL\n"

tell application "DEVONthink Pro"
   set itemList to selection of front window
   tell front window
	repeat with anItem in itemList
	   set itemName to ""
	   set itemLink to ""
	   set itemName to name of anItem
	   set itemLink to reference URL of anItem
	   set dataString to dataString & itemName & "\t" & itemLink & "\n"
	  
	end repeat
   end tell
  
end tell
tell application "Finder"
   set the clipboard to dataString as Unicode text
end tell 

• Create the desired paragraphs in DT and export them with DT back-links**. The TB end is to generate a set of notes that are text paragraphs linked back to source in DT.
• Use custom OPML export to export whole source doc texts with their DT back-link. You would then explode these manually and as soon as possible delete any obviously unwanted paragraphs. An agent can link these notes both to their TB source note and copy the latter's DT back-link the paragraph notes. If you save the $SiblingOrder of the exploded paragraphs to a custom attribute before weeding, you'll have the source paragraph number in the note.