I think it should work on older Kobo's, if Calibre can recognize your device, you should be ok. This is where I found out how to do it: https://theaccountabilityblog.com/how-to-export-highlights-annotations-from-a-kobo-device/
For the Planetfall series, I'd only recommend reading "After Atlas (Planetfall #2)" before "Atlas Alone (Planetfall #4)" as these two books are the only ones that are very close together in terms of timeline (Atlas Alone is a close continuation of Atlas Alone). My reading order was:
- After Atlas (Planetfall #2)
- Atlas Alone (Planetfall #4)
- Planetfall (Planetfall #1)
- Before Mars (Planetfall #3)
Cheers!