I do not know the answers to 1) and 2). For 3), the answer is no. Basically, for the same reason that you don't get to set your .exrc while compiling your Linux. Cpan is a tool, and it will allow configuration the first time it's run by a user. Different users get to pick different settings. For question 4), I'm unfamiliar with those settings, but judging from their spelling, one seems to be related to Build.pl, the other to Makefile.pl. But this is just a guess, assuming the author(s) picked sensible names.