in reply to
what format should Makefile.pl be and where is the list of attributes
Using ExtUtils::MakeMaker is preferred.
The 'repository' stuff ends up in META.yml, which is what search.cpan and metacpan (and a load of other sites like cpandeps) use, and you can also do it with EU::MM. Look for 'META_MERGE' in the doco. However, META.yml has historically been a bit of a moving target and some fields - including 'repository' - have moved around, so consult the documentation to make sure you put them in the right place.
The current spec for META.yml is at CPAN::Meta::Spec.