I break out my code with subroutines simply for the sake of readability and organization.

That is great for Perl4 code but you should really start using the warnings and strict pragmas in your code.

2) My understanding is

split has an exeption to the rule that the first argument is always interpreted as a regular expression and that exeption is a string with a single space character.    It is almost like split( /\s+/ ) except that any leading whitespace is ignored.    The exception is there so that Perl can imitate AWK with the -a switch.