Liquid Levain and Culture

I am reading the French Culinary Institute's bread program manual and I have a few questions. The book is incredibly vague. It basically just lists bakers percentages and than more of a bulleted list of instructions designed to be used by a professional baker as key points which they would then fill in details from their own experience. I am looking specifically at the pizza dough recipe and trying to compare it to PR BBA napoletana recipe. It has lead me to two questions.

The FCI recipe calls for a levain build. It than states Culture 10% 

It also calls for 10% Liquid Levain in the final dough. It then states on one of the bullets (improved mix)

My questions are these....

for the levain build, am I to assume that culture is a basic seed culture? I would normally not have access to this and would need to start a sourdough build?

Liquid Levain I am assuming is just another sort of start with higher hydration? 

Improved Mixing method, I have read that you basically mix for 5 minutes on low and 2 minutes on high adding oils and fats after initial gluten development has been achieved.  Is that a correct assessment? 

Thanks for the help