That setting might cause a problem if it is empty but it should have been corrected have you emptied it manually?
The comment is "Template path from version 3.0.4. If this file exists, it will be used as default source for new private namespace start page template (clear the path if you don't want to)."
As I just did a clean install of userhomepages, I didn't have a path from 3.0.4, so I cleared the line.
I don't get what you mean about the datestamp, there shouldn't be a copy yet...
The documentation seemed to imply I should copy it by hand. I deleted it, regardless.
Looking at apache2's error.log, I see
[Tue Oct 07 17:43:15.475084 2014] [:error] [pid 7977] [client 192.168.253.98:41908] PHP Warning: copy(/etc/dokuwiki/../data/pages/users/userhomepage_public.txt): failed to open stream: No such file or directory
Why on earth is DOKU_INC set to '/etc/dokuwiki/' It should be '/var/lib/dokuwiki/inc'