Gary - others have instructed/suggested you wait. Here is some information that might assist you in deciding whether to wait for Adobe's tool or DIY.
The most reliable advice for moving your Aperture libs to LR can be found at:
http://lightroomsolutions.com/articles/migrating-from-aperture-to-lightroom-where-do-i-begin/
This page started several years ago and remains alive. Be sure to review the comments section below the actual article to capture up to date experiences and advice.
As to understanding the differences between AP3 and LR5 at the DAM level. Invest 35.00 and purchase Peter Krogh's book at:
http://thedambook.com/organizing-your-photos-with-lightroom-5/
Personal experience is that both sources cover the essential elements of migration and building out the DAM. Admittedly, the missing link or question yet to be addressed is how much, if any, metadata and AP3 edits will be brought over to LR5 from AP3 by the tool set to be offered by Adobe. Depending on how much metadata you have in AP3, my guess is they will use XMP sidecars. As to edits, that's a different story and may well require some engineering.
I have spent the last few weeks migrating my AP3 libs to LR5. Using xmp sidecars most metadata came through. Edits, unfortunately were lost. So right now I am holding my AP3 library as is and everything new goes into LR5. I suspect that unless Adobe pushes out a robust migration tool set, a lot of us will be holding on to our AP3 libs, and bringing over our best images to LR5 and re-editing.
Hope this helps answer your questions.
ps here is the gospel from Apple on export:
Using Aperture, you can export photos (both versions and copies of originals), projects, albums, folders, audio clips, and video clips in a variety of ways.
When you export photo versions, you can export them in JPEG, TIFF, PNG, and PSD file formats. You can rename files, resize and adjust images, and include metadata such as EXIF information, IPTC information, and keywords. You can also apply ColorSync profiles and watermarks to the versions youre exporting. You can export separate lists of metadata for selected photos as a file. And you can export originals with IPTC data stored in XMP sidecar files that can be used in other applications, such as Adobe Photoshop.
An easy way to export photos is to use one of the Aperture export preset. Presets, or groups of export settings, allow you to efficiently export your photos in any of several common formats. If the presets included with Aperture dont meet your needs, you can create your own presets, modify existing export presets, or delete presets you no longer use.
When you export projects, folders, and albums (or a combination of all three), Aperture consolidates the originals and versions of the items you selected in the Library inspector and exports them as a library, maintaining their organizational structure. You can then merge the exported library into the Aperture library on another computer.