Just learned that NS is truncating our item fields when we download them via saved search - which means that we can't use CSV export / import to edit the those fields - anyone have a workaround? So frustrating....

I don't know if would work but have you tried pulling the item data into a formula text field instead to see if it stops the truncation?

Using the internal ID vs the Name/Display name is the most sound method for csv imports.

You can set your preferences to show the internal IDs on all searches, so you don't have to remember to add the field.