I think its one of those things that has never been updated. But to be honest? Outside of pfs I doubt anyone will argue against it and Ibtbink the rai is such you would be fine there.
Yes as albatoone said and gave you the reason. It is an archetype not a new bloodline; this is why you can't take mutated bloodlines with eldritch heritage feats, because they are not actual bloodlines.
Yes, absolutely. You are a sorc with the infernal bloodline. You have a sorceror archetype called Wildblood that modifies the features you get from that bloodline, and calls these changes "Pit-Touched". It still counts.