"Dropping PH from 7.0 to 5.6 is what? Almost 150 times more acidic?"
25X more "acidic". However 7.0 is considered neutral which is what makes the scale "sensitive" around 7 ... Because it is 25X more acidic than a neutral solution. In common speech that is 25X
nothing 
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"the data showed we have been cooling for 18 years"
Atmospheric CO2 concentration is not being debated by anyone, not even the politicians. No need to discredit NASA rather than addressing what you think is wrong with the CO2 in our context. It is just measuring how much CO2 is in the air, just like oxygen is 21% we have an average CO2 in the air. Forget I mentioned NOAA, NASA or whatever agency if you don't like them. 400 ppmv CO2 is roughly the baseline growers find when they control the amount of CO2 their plants receive in efforts to boost production.
"I add acid to my rainwater, I need it at 5.5 and I have to add a lot of acid to bring it in line."
"I have also observed that in the winter when I'm not watering the soil PH creeps up to as high as 6.5. "
It sounds to me like you are using your rainwater as dilute pH down for your soil (Maybe I'm wrong about that), and not discussing the buffering capacity of rainwater which is nil unless it is being contaminated. It just seems like you are using the rainwater to deliver the acid to neutralize a soil with a lot of alkalinity and tends basic every time it rains. The latter is completely understandable and seems to me a reasonable technique way to deal with alkaline soils when growing acid-loving crops.