Intent doesn't need to be proven. If you knew of the material non-public information and you then decided to execute a trade you're guilty of insider trading.
Actually there are three criteria:
1) Information is material
2) Information is not public
3) Breach of duty through the "trust and confidence" clause.
It would be highly unusual for the CFO not to have the burden of confidence but even for a division president it's not clear they'd have corporate officer responsibilities.
During compliance training in my old life they covered the classic "overheard in a coffee shop" example as a way to highlight that a barista does not owe confidentiality to a random public company. However, I don't think it's ethical behavior regardless of whether it'd result in a conviction.
yes if your employer loses all trust in you its one of the things they can sack you for and this also can be collective ie I know one of my team stole xx£ you can fire all of them - which surprised me when I first heard about it.
