In Europe for 90 days, need a gameplan for the last few days

I'll be in Europe (Switzerland, mostly) for 90 days. Once I get the data axe for exceeding 80 days of international usage, what is the best path forward for the final part of my stay? I have unlimited Premium.

I understand that I will still get calls and texts, but I have some questions. (Sorry if this seems ignorant, but I am old as dirt, and any technology newer than the internal combustion engine is incomprehensible magic to me. )

Texts/ WhatsApp messages/email with attached photos & video - Will I get the photos/videos if I am not connected to wifi? How about if I am connected to wifi?

Can I install a sim card and use it to provide the data to my googlefi phone #, or does it act like a whole other phone account?

I use the phone for business, and need to be reachable.

How best to handle the final bit of my time in Europe? Thanks!