Hey all!
I have a question for you guys who fly internationally to Mexico more often that I do.

This last June, I flew from Austin (KAUS) to Monterrey Del Norte (MMAN) with a couple of friends, and a CFII on board with us. We used the CFII's ticket to file IFR both ways. Becuase it's been a few months, there is something that I don't remember, and nor the CFII remembers HOW we did it.

1st Question.
I understand that you must be on an active IFR flight plan (or DVFR) when crossing the ADIZ. On our flight BACK to the United States, our handler in Monterrey completed and filed our Mexico ICAO IFR Flight Plan with the Mexican ATC system. Of course, I also called CBP 1 hour prior to departure to notify them of our arrival back into the US.
Our flight back to the US was uneventful. But here is the question... other than the IFR ICAO flight plan that was filed for us in Mexico, do we ALSO have to file and open an IFR flight plan with the US FAA?
I remember doing an ICAO FAA Flight Plan on my Garmin Pilot EFB, but I don't remember if it was filed or not. Is the Mexican flight plan good enough for our return trip?

2nd Question.
If we want to fly from Mexico to the US in VFR conditions, how can we file a DVFR flight plan with the Mexican ICAO flight form? My understanding is that you can only file V for VFR and I for IFR.

Thanks for your help! Please let me know if you need any additional details if it helps better answer my questions!

-Ranferi