For a different card you've never held, you should always get the bonus...I think it's for cards you may have already held with the same account where the answer to that is unclear, and likely depends on how long ago you held the same card.

You can always just call to confirm you'll get the bonus by looking at your account. It's possible that you cannot do a switch for a higher level of card without a credit check though (since the Prestige requires a higher annual salary/household income, no?).

They will always reverse, or at the very least, pro-rate your AF if you've changed your mind or misinterpreted or been mislead on card benefits/bonuses...