My last trip to Italy (general Naples area) was with film and camcorder, no digicams. But since then I've wandered through equivalent cities and villages (and museums) in Mexico and Central America, with my K20D. I hate swapping zooms around 55mm but your kit should serve you. It's probably too late for you to look for a used DA18-250, which really is an ideal tourist lens.
Yes, do take the Tak50! Metering is no problem -- it will work in Av mode, just don't stop down further than f/8-11.
I wouldn't bother with a 'pod, other than maybe a little tabletop job -- besides legs, mine also has a clamp so it can be secured to not-to-thick objects. For monopod-type steadying, there's the string-pod: a length of cord with a screw at one end (for the camera's tripod socket) and a big flat washer on the other end (for you to stand on). Just drop the line, stomp the washer, pull taut, and shoot.
While you're there, look for a theme. Mine is fountains with squirty-titted nymphs. Your proclivities may vary.