Doubtful. A microbe that thrives in an oxygenanated spacecraft hangar is probably not one that also thrives in sulfuric acid.
Such a microbe may have adapted to thrive in sulfuric acid. Unlikely, but it would be fascinating if it turns out to have happened that way...
We’ve been seeing these clouds of unknown reflectors for over 100 years, way before any missions.
Not absolutely impossible, but doubtful.
It's possible! But there's been been many instances of material exchange between the inner rocky worlds that could have seeded life on any or all of them. Either way, seeing evidence of flourishing biota on other worlds, be they local extremophiles or alien life, is exciting
I can’t imagine that enough time has passed for Earthly life to have spread as widely as the article suggests.