Its like what cigarette companies used to do- just constantly deny what's completely obvious.
There is an annoying combination of legal and commercial pressures that prevent the companies from going "actually it's more dangerous than we previously said" without it seeming like "it was a lie all along this is TERRIBLE".
The crucial take-away is that there is a bunch of additional geologic due diligence that the gas companies could be doing that would actually enable them to continue fracking. But the boom is driven in part by the utter dirt cheapness of it now and they're afraid of hopping off the wave.
No. It's completely positive. Methane has almost no pollution, and far less CO2 than any other large scale energy source.
The "contamination" is methane in water, which is harmless even if you drank it, and trivial to remove.
He picked the ones that seemed most dangerous to him, and they are all harmless. (But I haven't checked if there are others.)
Don't forget these chemicals are injected deep underground, so unlike lighter-than-air methane they won't easily get to water.
(PS. It's not "dumping" if you are actively using them. Dumping is the waste you don't need, no need for inaccurate emotive language.)
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[0] http://epa.gov/climatechange/ghgemissions/gases/ch4.html
A lot of the power infrastructure that handles peaks in demand (and averts rolling blackouts) uses natural gas. The question we need to be asking ourselves is which is the least bad alternative, because they're all bad.