As for Question 2, the simplest solution is to ask rename yes/no for every file. If there are many files, however, it's very easy to say yes where you meant to say no.

To avoid that problem, the utility could present the list of changes (in "from -> to" format) and ask the user if he wants to 1) rename all, 2) prompt for each change, 3) rename none. And maybe even 4) Specify which ones to rename (or not rename) by number.