#2 has also been answered in the affirmative, but the degree to which it is man made is open to some debate. But asside from a handful of cranks, no one doubts that human activity has had a significant impact.
The rest of your questions are all very much open to debate. IMHO, economists are probably better equipped to answer questions 5-6 than are scientists.
Over the past 100 years the earth appears to have been warming. Over the past 5, cooling. Over the past 20,000 warming. Over the past 2,000,000...
Define the time scale of analysis.
RE: #2 No, you're wrong. It is not "common knowledge" that anthropogenic sources are contributing (or not contributing) to climate change. It is precisely this that is the subject of intense scientific debate. It is not accepted fact that increases in CO2 levels in the troposhere have caused any changes in global climate. I expect that places me among "a handful of cranks."
None of these issues are settled.
Oh, on behalf of economists I would have to protest you're suggestion that they are something other than scientist.
I suspect most economists would prefer to be judged on the basis of their methodology.