First off make backups of everything (especially when trusting strangers on the internet to help you :-)

iPhoto/Aperture store the photos in libraries which are semi-opaque. So they need to be exported, your first choice will be if you want to export the originals or a version of your photos with any edits you may have made in Aperture -- this is your choice, edited versions will obviously have any fixes you made in them, but if you edited out something, it will be lost (for example you crop me out of a picture).

1. In Aperture with a library open, select all the projects
2. Right click and select export (here is where you need to choose the Original or Version)
3. Now you have the export dialog
4. Select the location you want to use to collect all your images (be sure there is enough disk space to hold everything).
5. Select the Export Preset of JPEG - Original Size
6. In the Subfolder Format select Edit...
7. Create an export folder preset to match your desired format - click the + at the bottom left and then drag the Image Year, add a slash, etc.
8. In the Name Format selection, pick this and select Edit...
9. Create an option to export with the original file name.
10. Click the Export Versions or Export Originals
11. Rinse and repeat for all your libraries