Don’t bother going to Venice. When writing fiction, I used to assume that I couldn’t write about things unless I had direct experience about them. I once wrote an entire story taking place in Chicago without having ever visited Chicago. But after doing a little Internet research, I was able to write a good and plausible story about Chicago which worked reasonably well — and nobody ever suspected me of faking it. (I later visited Chicago and confirmed that I got the details basically right). I am currently working on a story taking place in Venice. I never have felt “handicapped” because I never had the opportunity to go to Venice. You shouldn’t either. Writers get great at faking things; that’s the whole point of writing!
Stephen King once wrote that you should research the hell out of a subject (by interviewing people, reading nonfiction books, etc), and then cover your tracks by hiding as much of your background research as possible in the finished story.
I wrote stories about animals -- and often I will read articles about lifestyle and habitat. But you can't get too worried about what you don't know. Just try to imagine the best you can...(If you get a detail wrong, you can correct it later).
Also: I would try to read a book or two about the specific time period and setting. But don't sweat it too much. (For example, do you know that in Venice the locals don't ride gondolas but the cheaper vaparettos. Who cares though!) But as a nonnative outside the culture, people don't need to be impressed by your realistic details. I would worry more about plausibility; i.,e, would a Chinese character know about certain information from youtube, etc...