Ok, good, good. But uh... King William I of the Netherlands is of the House of Oranje... He is a descendant of the Prince of Orange and all the other Stadholders. And the 1830 Revolution was inspired by Louis-Philippe more than anyone else.
No, what he's saying is that the Netherlands never got a king until 1814-5. He wasn't talking about the king's national origin.
That is correct. As to the Belgian Revolution: there were several national revolts, following the Julirevolution's example in France, but the causes of these were local/national - in the case of Belgium the mentioned pro-Dutch policy caused a lot of bad blood.