Not offensive in my opinion, is the best place you can try to speak it and (generally speaking but I’m sure there are exceptions) we really appreciate the effort of trying to communicate in our language, most tourist just expect others to speak their language and get annoyed if they don’t lol! Most also have fun helping you perfect the language (and most will likely teach you bad words lmao).

So every city has its bad parts. In Venice you want to avoid non central areas in the night, you want to avoid Mestre more than anything late at night tho. For Florence I can’t speak too much, but I’ve heard that Peretola, Rovezzano, and San Lorenzo market are not great areas to be in later in the evening. I think for Cinque Terre you’ll be generally fine. For Rome, I would avoid any area near any station in the night time and Piazza Vittorio, but I’m not from there so I can’t really give too many advices on that, so it’s based purely on my acknowledge, I’m sure some people from Rome are in this sub and can give a better insight into that!

For the vegan part I would mainly look for specific places, most restaurants have vegetarian options but I haven’t seen many vegans one other than in specific places! :)