Hard to find exact data but 60-80% of the cost to manufacture ammonia comes from the cost of natural gas. Feel free to look a price charts for both to see the correlation.
Long term yes, however the building in such a plant is very expensive in the short term. As such, no one is going to build a plant unless they actually think it will have reasonably high utilization.
the methane isnt the issue, building and operating the processing plants is