I remember reading that newspaper ink is only toxic when it's wet, and that's wet as in 'freshly printed'-by the time we get our hands on it it's perfectly safe, and it getting wet through leaky water bottles or urine doesn't make it toxic again.
So, assuming that what I read was true, newspaper is fine.
Newspaper is fine, providing it is printed using soy based ink. Most are, but if you're worried ring them.
I've always put it underneath to lift out the bedding, and on the occasions where a pig gets naughty and digs it up and chews it a bit - I've never had a problem.
I use the colored paper like the comics section. I have two towels on top of it and then fleece. My girls don't bother with it. I think if they can't get to it, it'd be ok but to eat it, I'd defer to one of the mods on this one.