Take a look at the 8:1 setup here.
http://www.harken.com/blocks/Harken_mechanicaladvantage.php
Just "unwind" from the tie at the bottom and instead of passing the fourth time at tie top, tie off.

Call Layline and they can help you with the cordage, there is no "right" kind. Just options. Larger diameter is easier to hold but doesn't run as easy in blocks. Too small and you won't be able to hold onto it well.
Lots of different kinds of line depending on budget also.