Export EDITED photos from iphone, AND keep original date stamp

If you use iCloud Photo Library to sync the photos between the iPhone and the Mac, you will get best possible transfer. The edits will be transferred, the original dates, andyou can revert all edits to the original version. It is the only way to transfer the photos from the iPhone to Photos on your Mac losslessly.

The original date stamp is kept in the metadata within the picture, not the metadata of the new file created to hold the modified copy of the picture.

If you want to force the new file to carry the original capture date of the picture, there are third-party applications that can read the interior metadata and forge the file date to match. I use GraphicConverter for that; others here have cited other programs.

After you download the items with Photos from your iCloud Photo Library, you can select them all at once in Photos with ⌘A and use the command "File > Export > Export ... Photos" to save the edited versions to a folder outside of Photos, or "File > Export > Export ... unmodified originals" to save the precious, unmodified originals. I would always save and keep the originals, because they have the better quality than the edited versions, and they make it possible to correct the edits you applied.