I've not had a need or desire to own a cell phone, so I have a lot of catching up to do to best prepare for this trip. My wife's cell provider does not offer Intl. service. We will be purchasing a 2nd cell phone for this trip.
A smart phone is really useful for navigation, especially. Using Google Maps on my phone has saved me hours of time that I used to spend researching bus and train schedules, walking routes, etc. Last time I was in Venice, for example, I was out late one night taking pictures around San Marco. I was staying at a hotel near the train station. What's the quickest way to get back at 10PM? Instead of trying to guess which vaporetto might be the best option - or just walking - I asked Google Maps to guide me back to the hotel. It gave me walking directions to vaporetto leaving from Rialto - quicker than taking a different vaporetto but a lot less walking than just walking all the way back, something my aching feet appreciated. In the past, I might have tried to figure out the varporetto schedules...or just not bother and walk all the way back.
We will be visiting several museums where will be using 2 cell phones equipped with ear buds to listen to Rick's audio tours. In this case we will need to purchase 2 SIM cards-one for each.
No, actually, you don't need a SIM card to listen to Rick's audio tours at all. You just need to install his app, then download each tour to your phone. You can do that on WiFi, even now at home if you want or at the hotel in Venice before you do the tours. No SIM card or mobile service required.
Will a wifi device be of any advantage when using 2 cell phones-having to purchase 2 phone plans?
You should be able to buy two SIM cards for a month's service still for less than $99 to rent a WiFi hotspot. And if you do that instead of using the WiFi hotspot, the two of you can still use your phones separately. If you decide to do something apart for a short time, only the person carrying the hotspot will be able to use their phone. Plus, the hotspot is yet one more device to carry around, make sure it's charged up, etc.
Is texting common in Italy? Reason I ask is that I just read a forum reply that said the TIM plan does not include text messages?
I'm pretty sure all TIM SIM cards would come with texting. But, you can find other ways to text for free not even using the SIM card - with apps like WhatsApp (which you can also use for calling).
We are also bringing an iPad Pro Wifi 9.7". Am I correct that this model can be used as a "router" for the cell phones? Would this iPad also require a SIM card purchase?
Not familiar with that iPad. Some tablets are "WiFi-only" and can't accept a SIM card at all - and that means that, no, they can't be used as a "router." You are actually thinking of the "hotspot" feature both phones and tablets have in them - if a tablet can take a SIM card, it can be used as a WiFi hotspot exactly like one of those devices you are considering renting. You can share the TIM SIM card's mobile data via WiFi - just like the mobile hotspot. But, your smart phone can do exactly the same thing. When I take my Android phone to Europe, I use my Dutch Vodafone SIM and use my phone as the WiFi hotspot for both my laptop and my tablet. It's the best of all worlds for me.
A tablet that can take a SIM card is basically just a large smart phone. But again, some tablets can work on WiFi only and don't have a place even to accept a SIM card.