

It’s density that matters, and Venus has a very dense atmosphere. If you go high enough it becomes Earthlike in some ways. Landers can get certain data that is impossible to obtain from afar. Same reason we land on Mars. I have no idea how you’d begin to make a rover for Venus. It would break down in hours or you’d need to invent computers that can operate at several hundred degrees.
Yes exactly which is why flight on Mars is kind of tricky and flight on Venus (ignore the acid) or Titan is a lot easier