80C is warm, but not life-threatening to the chip. I'm not sure, but it may start to throttle at this temperature, as previous versions did throttle at 80C. So cooling is helpful, but not required (Apple ran inadequate cooling in their MacBook Pros for years). Also, I think that hitting 80 is only under heavy load. Regular use should be cooler than that.

You will certainly need to cool the chip to get any meaningful overclock. In that case it is different from previous versions of the Pi, when you could overclock a bit with no extra cooling at all.