> How do you like 900 degree temps?
I don't. But there's no need to go that deep. Again... look at a chart of Venus atmospheric pressures and temperatures. Find out what the temperature is where the atmosphere is one atmosphere in pressure.
Here's a hint: at that altitude, you need a sheet of Visqueen to keep your breathing air separate from the outside CO2... and a nice sweater to stay warm.
And here's another hint: CO2 is 50% denser than the O2/N2 mix on Earth... and hydrogen is basically inert in it.
Put it all together.
So you're proposing colonizing Venus by living in cities suspended in the atmosphere by balloons?
Actually I did read that with an Earth-like atmosphere Venus would have a planetwide temperature of about 87 degrees (Earth is 59 or 60). Hot, but tolerable, especially at higher latitudes.