Tacna is right at the border with Chile, and I think nomads have some karma with such cities. It feels very much like a typical dusty border town, although it is actually a sizable city. It is extremely arid, but the locals have clearly tried to green the place up a bit, like with the lush walkway pictured above. Additionally, there appears to be more than your average amount of singing and dancing, especially in the main plaza, although it’s very luck of the draw to catch it.
With the cafes, a number don’t have operational wifi. There are not a lot of suitable cafes, but here are at least a few that should get you through your stay.
Just a tip here that the websites that give bus information seem to only list companies that run like one or two buses a day between Tacna and Arequipa. For some mysterious reason, they do not list Flores, which runs buses like every hour, including cama buses. Note that Flores also has its own terminals in both cities. You want to ask for “Terminal Flores.”
Have a good stay in Tacna!