Will Perl 6 be 100% entirely compatable with perl 5.6.1+ scripts?

No -- that's why it's called Perl 6. That's the answer if you're asking if Perl 5.6.1 is forwards compatible with Perl 6. If you're asking about backwards compatibility, read the next question.

Will I be able to run perl 5 scripts with perl 6?

That's the plan, yes.

Even more importantly, how will modules be affected? Will they all have to be rewritten in perl 6 code before they can even be used?

Since Perl 5 scripts and Perl 5 modules are written in the same language, it's the same answer.

Second, I assume (yes, assuming is bad), that the majority (if not all), of the people rewriting perl are perl/system gurus. This makes me fear that the simplest of tasks will be difficult for a newcomer to the language to execute.

Why? These are the same people who made Perl 5.

Your code example reminds me of a .signature Simon Cozens had. It reads something like "Allowing programmers to program in English will only prove that programmers can't write English."