Only commenting on the last point. He's referring to the previous proposal from the final years of the Bush administration wherein Congress would have passed an internet sales tax if the various states (mostly meaning Cali and NY) would have agreed to simplify their taxation structures ahead of such legislation. The idea was that states would set their sales tax at one of several fixed rates (i.e., 5%, 7.5%, 10% etc) subsuming county/city sales taxes into the state tax rate. Counties and cities would receive their proportionate shares (though the mechanism for determining shares was never discussed in depth).

The proposal actually received a lot of discussion among policy makers, but then got dropped when it became clear that state legislatures wouldn't go through the trouble of reforming their sales taxes without Congress first passing the legislation.