what format should Makefile.pl be and where is the list of attributes

gideondsouza has asked for the wisdom of the Perl Monks concerning the following question:

So my question is pretty simple.

I noticed most modules use ExtUtils::MakeMaker and their Makefile.PL looks like this:

 use ExtUtils::MakeMaker;
  WriteMakefile( ATTRIBUTE => VALUE [, ...] );
[download]

But some distributions, like Net::GitHub look very different:Link to the Makefile.pl.

This seems to use inc::Module::Install.

Q: Which method is is preferred?
Additionally I noticed Net::GitHub has a repository attribute with a link to the github repo, I didn't know about this attrib, and it seems pretty useful since both search.cpan.org and metacpan.org will show this on the release info. Q: Where can I find a list of attributes needed/used by various cpan clients?