The current updates (if the Dlite does get one) are in Beta stage right now.... Which means they are optional to load, and your Dreamlink will not show any Beta update unless you specifically ask it to (by pressing 0227 and then the red button, while in the update menu).
So the only update that will be seen as an auto update or an update waiting to be installed, would be an Official update (out of Beta stage).
That is why the dates can be so far apart that you may see, because there may have been a few Beta updates that were not shown, but never the less were updates.
And no, you do not need to install any of these updates in consecutive order. You can choose not to install any Beta release and wait for the Official release version, if you so choose.
This very latest update is a Cumulative Beta release, which means it is prolly the 2nd or 3rd Beta update since the last Official one.
So with that being a Beta update, it will not show as an update in your Update menu, unless you press 0227 on your remote and then the red button.
It's your choice to install any new update, Beta or Official.
A factory default will not affect the software file/update that is currently on your Dlite, except maybe to help to initialize that last install (as BKman has inluded to)