Recall Knowledge checks are Secret, so you never know the results, other than a standard Failure. The DM should be rolling the checks. A Critical Failure acts just like a Success as far as the player knows. Typically, after a Success (or Critical Failure), the DC for further Checks would increase. A normal Failure prevents further checks.
Making 6 checks against 1 Creature is unlikely to be useful. You would want to spread the checks out among multiple Creatures.
Additional Knowledge
Sometimes a character might want to follow up on a check to Recall Knowledge, rolling another check to discover more information. After a success, further uses of Recall Knowledge can yield more information, but you should adjust the difficulty to be higher for each attempt. Once a character has attempted an incredibly hard check or failed a check, further attempts are fruitless—the character has recalled everything they know about the subject.
Hypercognition doesn't have a Target. You just make 6 Recall Knowledge Checks, 1 by 1, as they are individual Actions, about whatever topics you choose.
The description of Recall Knowledge seems to directly contradict the idea of multiple checks being unnecessary on a creature:
For example, Arcana might tell you about the magical defenses of a golem, whereas Crafting could tell you about its sturdy resistance to physical attacks.Also - yes, normally Knowledge checks are individual actions except here - where the spell specifically says that they are part of the action of casting the spell.
Yes, they are part of that Activity. They are still individual Actions within that Activity. The game does not have any framework for multiple Actions occurring at once.
I quoted the rules on Additional Knowledge. I don't know what else to say on that. It would be up to the GM to determine if he feels that Golems(Arcana) and Golems(Crafting) are different subjects.