I think you’ll be fine as long as you were truthful with the questionnaire. I’ve traded in six iPhones to Verizon via mail in the past and never had an issue. Don’t let these types of stories scare you.
I’m pretty sure Verizon doesn’t process trade-ins in their stores. They’ll just put it in the mail for you if they do take it. Best to mail it yourself rather than introducing a middle man to the process, imo. It eliminates someone else from potentially doing something wrong and playing the blame game. Be sure to take pictures first.
Don’t get the phone replaced under Apple Care. Didn’t you have to provide the phone’s IMEI when starting the trade-in (or select a phone that was used on your line)? I don’t think they’ll accept the trade-in if they receive a different phone, even if it’s the exact same model.
EDIT: Maybe you can trade-in at a Verizon store. I’ve always read otherwise, but found this on their site: “Bring us the device you want to trade. Use our
Store Locator and filter for "Verizon Company Store". Authorized retailers don't accept trade-ins.”