"The fact that I'm having trouble accomplishing #1 (i.e., unable to hack mod_rewrite sufficiently that index.pl is hidden, or even that it depends on mod_rewrite)"

httpd.conf:
ScriptAliasMatch /rest\b /path/to/index.pl
http://somewhere.com/rest/candidate/4/vote/yes

or:

ScriptAliasMatch /candidate\b /path/to/index.pl
http://somewhere.com/candidate/4/vote/yes