[starwaver]

For the first problem, we can probably build small "launcher" platforms from lighter gases so it brings the spaceship to an altitude with much less gravity.

The sulfuric acids should be fine with enough protective coating. Earth's atmosphere isn't all that friendly either with rust able metals. Thus we have corrosion-resistant paint.

[stcredzero]

For the first problem, we can probably build small "launcher" platforms from lighter gases so it brings the spaceship to an altitude with much less gravity.

Uh, no. Sit down with the equations yourself. The main way one counteracts gravity is by gaining orbital velocity. Astronauts aboard the ISS experience almost as much pull from Earth's gravity as you do on the surface. It's that their orbital velocity puts them in a frame of reference that has "microgravity."

When I posit launcher platforms on Venus, the point is to launch from a higher altitude, thus avoid some losses to air friction, and also to use the entire station as reaction mass for launching the payload from an electromagnetic cannon. Doing this avoids the near-exponential nastiness of the rocket equation.