Here's a tip to avoid Reaper inserting your consecutive files back to front/upside down order (when using the right-click actions, 'insert into project' and 'insert into project on new track')...
Click on 'name' in the explorer so the files read in ascending order...then they will insert correctly!
Back to front I know, but it works...(a windows fault apparently).
Discussed here:
http://www.cockos.com/forum/showthread.php?t=21631