Q: Whether and how much China is stockpiling commodities and raw materials, and the impact that behavior might have on US/global inflation and the China economy, especially its banking system？

A: We don't know how much China's record imports are for stockpiling.  As far as I can tell investment in manufacturing sector is very weak.  Property construction was very low until now.  The revival in sales may give property developers cash for supporting contruction.  The demand for commodities may pick up some from the low base.  Still,the situation doesn't justify record imports. The current demand level is much lower than last year's.  I suspect over one third of the current imports are for speculative inventory piling.
 
The CRB commodity index is nearly up by one third from the low in 2009.  Its inflationary impact is already felt.  For example, for food processing industry, every type of raw material began to inflate in April 2009.
 
For the US oil price has doubled from the bottom.  This is very bad news for its economic recovery.  For low incomefamilies that are hit hard by the debt crisis, their extra pay for higher gasoline price is about 2-3% of their household income.  Of course, they can spend less on others and the economy can't recover as long as oil price keeps rising.
 
The Fed can be forced into raising interest rate soon, probably before yearend.  This is because the inflationary impact form commodity speculation.  The rising interest rate removes the last hope for a quick economic recovery.