Bologna is a wonderful City, with a fascinating history, remarkable cuisene, and friendly people, even if you cannot speak Italian. As Americans we really loved the fact that, apparently, not many English speakers go to Bologna. We heard almost no English in the areas we explored. That is actually a big plus; it means B. is where Italians and other Europeans go, thus you receive a more immersive experience and not simply a "tourist" experience. Here are some suggestions:
1. Take this free tour asap after you arrive (yes, free, but do tip your guide st the end, since she/he will give you a brilliant introduction to old Bologna.) This is the "real" free tour site:. https://freewalkingtouritalia.com/
2. Be aware that Marco's apartment has a plain door on the streetside (it's an entrance to an apartment building, with many names/buzzers on a keypad beside the door.) The image of the apartment on the Airbnb site is from the small courtyard you reach when you walk up the interior stairs & reach the open-to-the-skies courtyard).
3. The apt. is right beside Ristorante Teresina, @ 4 Oberdan St. (We almost ate there, but after our free walking tour at 11am on Sat., when we were introduced on the walk to Piazza Santa Stefano, we decided to go back and eat there.) Go, go, go to that Piazza!!). See, https://www.bolognawelcome.com/en/home/discover/places/architecture-and-monuments/historical-buildings-and-streets/piazza-santo-stefano/
4. We ate at Restorante Cesarina, on the Piazza. It was a wonderful meal, we took server's recommendations for local dishes (there is also a symbol beside the dish descriptions which indicates "typical" dishes.) It's a 100+ year old restaurant and we would go back in a heartbeat. BTW, we had no reservation & outside seating was booked, but the interior is wonderfully "Italian" in ambience. https://www.ristorantecesarina.it/
5. General note about outside seating in Europe, true for our meals in Amsterdam, Verona, Vincenza, Padua, Venice, Bologna, is that smoking is allowed outside. The chances are good that there will be at least one or two smokers nearby, at least before or after they eat. Don't necessarily let that dissuade you from sitting outside (we would have loved to sit on the Piazza Stefano in the early evening, but all outside was reserved !), but smoking is still prevelant in Europe it seems, much more than we see in the US.
6. Step inside, at least, the library Biblioteca Salaborsa, which is beside the Neptune Fountain at Pizza Maggiore. It is an amazing interior, with wonderful library signage (I'm a retired librarian, though), but the main room is spectacular & entry is free.
7. Marco's apartment is very stylish, the air conditioning wonderful to have, very clean overall, and a great shower. And so convenient! It is a 15-16 min walk to the train staton, so perhaps doable for you if you are very mobile and don't have lots of luggage (we have Rick Steve's basic travel canvas bags, with backstraps which are hidden, until you need them ... excellent travel bags, which no problem on transatlantic flights or Lufthansa/Italian planes, as carry-on.)
Finally, the old city center is closed to traffic on Sat. & Sun. which makes Bologna come alive with people (we had sunny skies our 2 days there), and it was magical for us. If we return I will definitely arrange to be there during the 2 weekend days.
Enjoy Italy. It's an amazing place to visit!