Does anyone know if we will receive a NEW card in the interim?
No one can answer that with any certainty. If UCIS has renewed your conditional status for a year, it's likely because they are very behind.

Sure, we have the letter, but is that good enough??
Yes:

May I travel outside of the United States while my I-751 is pending and my alien registration card has expired?

Yes, while CIS is processing the joint petition or waiver, you can travel abroad even if the conditional resident card has expired. The CIS will issue you a receipt once it receives the I-751. The CIS receipt serves as proof of your continued lawful status in the United States. A conditional resident can use this filing receipt and the expired conditional resident card to reenter the United States following a trip abroad. It is important to be aware of the expiration date on the receipt and to reenter the United States prior to that date.