Quick question about the errata regarding master professions

A qualifying skill is any skill that can be purchased from a regular Profession or Master Profession that you have and that is associated with the Master Profession. Each regular Profession is only associated with one Master Profession and each Master Profession is associated with addition purchases of itself.

Does this mean that any and all purchases from a list with an associated master profession will be counted towards that profession?

For example: Cleric is associated with Master Warrior. Do purchases of prayers from Cleric also count towards Master Warrior and not, say, Arch Caster? From how it is worded, I would expect this to be the case, but wanted to make sure.

Also, I would assume that build spent on opening a list does not count towards a master prof, correct?

You are correct that build spent towards prayers on Cleric count towards Master Warrior. If you were a Cleric and a Priest, you could count them towards either Master Warrior or Arch Caster, but not both.

Build spent to open a list counts as build spent on that list.

I was curious as to how racial lists were counted in.

They aren't. Build spent on racial skills don't count towards any master list.