Actually if it's that hot there, you could use the heat to power steam turbines that generate power to air condition the entire planet. This sounds flawed though.
CO2 is actually a good thing, load it up with plants, and you'll get O2.
With a more conducive atmosphere, it's feasible average daytime surface temperatures could be *tolerable*, but one wouldn't really want to go doing much vigorous activity. And again, with a better atmosphere, nightside would probably be quite comfortable.
Air condition would most certainly be recommended for any surface dwellings, that much seems certain. But it probably wouldn't be a "bake you instantly" type temperature.
Of course, it is that way right now, but that is due to the runaway greenhouse effect. Venus, Earth, and Mars are actually remarkably similar planets. Earth became the goldilocks thanks to abundant water and, for our sake, a "perfect" atmosphere. Mars and Venus went opposite directions - Mars likely just didn't quite have enough mass/density to establish a solid gravitational lock on an atmosphere - evidence suggests it had a very well-established atmosphere, likely similar to ours, but weaker gravity and a weak magnetosphere allowed solar winds to strip away the atmosphere.
As for Venus, I'm not sure about the properties of its magnetosphere, but the atmosphere was allowed to grow more and more dense; with it being almost entirely CO2, that also allowed a well-established greenhouse effect to take hold.
If we could not only turn some into O2, and additionally siphon a large portion of the atmosphere away, temperatures would be nowhere near the insanity levels we have witnessed - it's not close enough to the sun to truly have unbearable temperatures if the atmosphere was far less dense. No atmosphere, and the nightside would be unbearably cold too. Most likely, if we can tame the atmosphere, we could create dome-style habitats quite feasibly - with exposed-surface walks being possible with protection.
Does it have a weak magnetosphere? I see discussion of radiation... that isn't really feasible fix for humanity, not in the next millennium at any rate - so the radiation variable would remain dangerous - but domes plus a less-crushing atmosphere? Doable - in time.