Newt pledged not to go negative, but in the same breath he "reserved the right to tell the truth" about the "Massachusetts Moderate." Newt speaks in incendiary tones whether he means to or not, it's just his style/nature. His biggest problem is that, without a lot of surrogates, he does not have anyone to do the dirty work at arms length. I cannot imagine after getting "Romney-boated" (Newt's term) in Iowa that Newt will play nice. It was an experiment (again, his word) that failed.
So, I would like to think it will be different this time but you're never disappointed if you expect the worst.
Agree on the religion, although Santorum and Gingrich are both Catholic. As a Catholic living in the South, I can tell you that many don't view us as Christians either. Perry has been the only one whose supporters have openly questioned Mitt's religion, and it looks like Perry may not stick around long enough to do it. But there are not a lot of LDS tabernacles down here either, so I am afraid you are correct that such an attack will come.