Traveling while STEM OPT Extension is pending

[Abi K]

My OPT expires on January 2, 2018, and I expect my new EAD card (with STEM extension) to arrive the week of December 26, 2017. I'm planning to travel to India in December and return on January 1, 2018 (1 day before my current EAD expires). I’d like to understand the rules a little better so that I can make a sound judgement call on my risk of traveling.

• If my STEM OPT extension has been granted at the time of re-entry (i.e. new EAD card arrives at a relative’s residence in the US before I get back on January 1), do I need to present the new card at the port of entry? Or can I present my current EAD card expiring on January 2 along with a scan of my approval notice / new EAD card?
• If by the time I get back on January 1, I haven't yet got my approval notice (holiday processing delays, an RFE, etc.), is it probable that I'd be denied entry with 1 day of OPT remaining (assuming I have all my documents)?

Appreciate your guidance!