Sorry for missing your post - perhaps the issue has solved itself? It sounds like you're adding data to an existing file, and as long as the field types and lengths are consistent, then there should be no problem in Access. If your seeing the data in a different order when you then view the Access file, my guess would be that you're exporting with a different sort order to the one that's active in Monarch's table window?
For Excel, there are two other issues that might affect the export - named ranges can get corrupted, so Monarch can't put the data into the right place, and you can exceed the row limit of Excel, so you end up with a corrupt file.
Hope this helps,