1. It's of course your decision, but you would be well-advised not to provide sensitive data such as e-ticket numbers to anyone via social media unless you are using a verified account, e.g. a carrier's official Twitter account or somesuch. You don't know that the person you spoke with is a DL employee or, if she is, whether she's disgruntled.

2. The ticketing carrier needs to deal with this and the rules are no different as between DL & KL. Both will offer you a refund. EC 261/2004 does not apply to a ticket between two points outside the EU (LED & MSY), but even if it did, Guidance issued by the EC back in April makes it clear that Section 8 can be limited to a refund during -- not necessarily as the result of -- the pandemic,

3. Keep trying with DL and don't give up if your #1 reroute is not viable. Have Options 2-10 written down as well.