There are to main reasons why gas giants are unsuitable for life. 1. the atmosphere of most gas giants are toxic to most forms of life 2. the gas giants are giant and so have gravity ten or even hundreds of time stronger than Earth and so life is under extreme pressure and would be squashed by the gravity

the main sequence

At some point, eventually. But Venus is more than 100 times farther than the Moon even when it is closest to Earth. It would take a long flight to reach there and return, and the technology barely exists to survive the crushing pressure and incredible heat on the surface of Venus. Soviet landers have functioned for no more than 2 hours in those conditions.

It may be easier to establish a "floating" scientific base in the upper atmosphere, where it is cooler. The problem there is that the winds will carry your base around the planet as the atmosphere circulates. That and the droplets of sulfuric acid that form the clouds.