Well, the law doesn't really say anything beyond "manipulative devices" and "contrivances," but right now, judges have kinda ruled that intention matters. But we don't know much, because most of these cases get settled out of court, so we don't have a robust case law to base any of this off of. Basically, if you participate in a financial transaction in any way, be prepared to be accused of a crime.

Intention mostly matters, sometimes doesn't. Sometimes the left arm doesn't talk to the right arm and conflicting orders go out. Technically this could be construed as spoofing, but sometimes it's business unit A not talking to business unit B, because A isn't in the same location as B, or there's a Chinese Firewall between A & B. It might not be intentional spoofing, but it can happen, anyway.

The law strongly disagrees, and for good reason. See: manslaughter vs murder.

it matters because the law says it matters.