Exobiology and extremophiles

Factual Questions
1

From Wikipedia:

An extremophile (from Latin extremus meaning “extreme” and Greek philiā (φιλία) meaning “love”) is an organism that thrives in physically or geochemically extreme conditions that are detrimental to most life on Earth.[1][2]

Documentaries that ponder the existence of life on Mars or the under ice oceans of Europa often point to Earth’s extremophiles as potential proof that life could indeed be present in these environments. I hope that they find life or evidence of past life on Mars or elsewhere, however, a thought occurred to me that I’ve not seen covered in these documentaries. Is it possible that extremophiles exist only because life began in more hospitable conditions and subsequently found it’s way to the environments that extremophiles inhabit? Is starting life as an extremophile far less likely?

2

I think the mainstream view would be: Yes, entirely possible.

Based on current evidence, hard to say. To give a meaningful answer to this question, more information than is currently available about the detail of how life begins would be needed.

3

IANAB, but I wouldn’t be surprised if our current Oxygen atmosphere would be inhospitable to starting life. All that Oxygen reacting with chemicals, breaking them down before they became very complex.