[agapos]

"So is it old, buried organic (flora, fauna) matter thats causing the methane ?" Yes, I believe so, though it could be still younger than the normal gas and oil fields (personal speculation).

1.) I think it may be possible, using a mix of infra and normal optical observations with a good algorithm to identify it on the images. Another but even smaller possibility would be the inspection of differences in the gravitational field * (though there may not be enough gas to be measurable this way).

But for either of these to be even remotely possible, we would need a good idea of what to seek, namely a not-yet-popped methane lens under the permafrost.

2.) Unlikely. Suppose if we manage to find some intact ones, tapping into those would be dangerous to a currently unknown extent, maybe even compared to the normal hazards of working with explosive and flammable hydrocarbons. Secondly, the amount of gas may not be enough to clear the costs.

Edit.: * Gravity gradiometry