Haha, you can expect to spend 8-12 hours a day at it. I don't know why, but it's like being one of the seven dwarves.
Niche writing is the way to making a name for yourself. Don't stray from your niche until you have something of a name for yourself among your peers and audience in that niche. As for atheism, that is going to be a tough nut to crack in this medium. Atheists gravitate toward podcasts and popular blogs. You are very unlikely to find publications that want a columnist in the atheism niche. Your best bet is likely to build up your own stuff and get people to advertise on it to make money. Then, write books that go with your (hopefully popular) site.
Niche writing is the way to making a name for yourself. Don't stray from your niche until you have something of a name for yourself among your peers and audience in that niche. As for atheism, that is going to be a tough nut to crack in this medium. Atheists gravitate toward podcasts and popular blogs. You are very unlikely to find publications that want a columnist in the atheism niche. Your best bet is likely to build up your own stuff and get people to advertise on it to make money. Then, write books that go with your (hopefully popular) site.