We have performed an external campaign which drove traffic to a series of 9 separate pan-European countries ... I am looking to find out how many of those visits during that period of time were new visitors (ie. first time visitors to those pages) ... AND.. I also would like to know how many of those new visitors then went on to repeat visit those pages - again, in the same period.
Adobe Analytics might have default segments or at least we can easily create our own segment, see here: Compare new visitors to return visitors
Ideally you are looking at the visit number of the visitors: if a visitor has at least one visit with a visit number higher than 1 (2 or higher) the visitor is segmented as "returning visitor". all others are segmented as new visitors. be aware that this is not depending on the timeframe you are looking at rather segmenting the visitors in their whole history!