If anyone is interested in learning more about permafrost methane, and a bit about clathrates as well, this paper[1] is a pretty good primer. I worked with the lead author over a summer around when he was publishing this a few years back. It's possible I can answer your questions, although I won't guarantee it. Clathrates/hydrates are a personal favorite of mine, even wrote up a short research paper in grad school on the possibility for their economic extraction.

[1]http://www.climateemergencyinstitute.com/uploads/L_Livermore...

EDIT: The URL is a bit hyperbolic, but the paper is legit, it's just the first host for this paper I found.