About the only info you'll be able to really get is
via this guy, who wrote a handy .mbp extractor and made notes about what he noticed when writing up his program.
Of course like everything else having to do with Mobi, the format is not open and poorly, if at all documented. Amazon is simply not interested in sharing much and everyone else who wants to work with their stuff basically has to stick with the officially supplied tools or reverse engineer on best guesswork.
I myself have noticed a distinct difference between .mbp files generated with the K4Mac app, and those generated on my K2 with the 2.5 firmware upgrade.
Pre-2.5, .mbp files all included the text of the highlight as well as the notes. Post 2.5, only your actual notes seem to be included, with pointers to the presumable internal location of your highlights being substituted. I think this is what makes K4Mac notes (generated in the old style) unreadable on a Kindle hardware device, although newer versions of K4Mac seem to have no problem reading Kindle-generated notes.
In any case, if you make a lot of notes and want them to at least be exportable, then the MBPreader script will still work to export your notes.
Unfortunately, you're stuck for the highlights (which normally get exported to MyClippings.txt on a hardware Kindle, which you don't seem to have, and only if they were made on said Kindle).
Although it might be possible to tweak the script in conjunction with some of the Mobi unpacking tools and get it to look up and export the highlights from their references, if anyone manages to figure out the pointer syntax.
Hope this helps.