It has an "atmosphere"
It's 0.00628 atm according to Wikipedia. That's effectively a vacuum. You can't have liquid water on Mars.
So you can grow plants in some kind of transparent pressurized place... Just like on the Moon.. or on a space station
So you can grow plants in some kind of transparent pressurized place... Just like on the Moon.. or on a space station
You can use ISRU and atmosphere resource extraction to generate rocket fuel on the surface of mars, rather than being restricted to the rocket fuel you bring with you.
Ultimately, the answer is Mars has the necessary resources and when you look into the details just makes more sense and is easier.
That depends entirely on the effect in question.
You'd have a hard time pressurizing the moon's atmosphere to harvest it for propellent.