Pages: Linked columns
Pages is not at all set up to do what you ask. The layout in iBooks author is superior to Pages, but you can't easily share that work across platforms and until the next versions of Apple OS ship (presumably in the fall of 2013) - iBooks author lets you design on Mac only and read on iPad only.

The text in multiple columns flows from the bottom of one column and up into the next. Additions and deletions will not align well unless you use a table structure to hold paragraphs and enforce the right-left constraint so that one comment isn't higher or lower vertically than the text for which it corresponds.



Hopefully tables works for you, as your other option in Pages is to use the comments or track changes feature to anchor some amount of text to another specific portion of text. These items do print nicely, and you might find you can use the whole width of your page and let the software reduce things to fit as needed.