I suggest the images that are in the Aperture Package folder/system you Move them, Using Finder, to the external drive in year/month/day (or whatever combo of those 3 you like) and then "Simply" Start Over in LR by importing them from where they are located on the external drive using the Add option at the top of the import dialog window.
I personally would not try to use any Aperture > LR plugin to try and convert > import the current Aperture library/catalog to a LR catalog.
I, Not Knowing, exactly how Aperture works if it store the edits in its library file I would first Export those image as TIFF's so I had a record of them and place them next to the original RAW files. If all you shot is JPG then I wouldn't really worry about it.
I would recommend method 3: use the primary organizing tools in Lightroom, those are keywords and other metadata.
Do not try to use folders to organize, other than by capture date. Do not use collections as a primary organizing tool.
Keywords and other metadata have several advantages over folders and collections. And using keywords and other metadata is easy to do in Lightroom, and you don't have to move photos from one folder to another (which for some reason, new Lightroom users have trouble doing).
Echoing this comment:
- Folders only for physical storage and safekeeping - backup, restore, use of disc space
- Categorise and analyse your photos by assigning keywords and other IPTC metadata like the job field
- Use Collections for gathering and grouping pictures for specific needs
Don't routinely move stuff around - it only undermines whatever backup you've made of those files.
Re the comment "SOME images within the Aperture library package", I would suggest making all files referenced before transferring.
I would certainly suggest using Lightroom's from Aperture plugin to bring in your Aperture library. Backup everything first, so if anything goes wrong you could take an easy step back. Secondly, with all your files referenced in Aperture, I recommend you review the options in the Import from Aperture dialog box and choose the option to import files in their current locations. More here.