I think the OP has a valid point. Anything requiring a third party goes against bitcoin's philosophy.
I don't think so, but for mainstream acceptance a little help from businesses is going to be needed. With anything that becomes popular capitalists will try to capitalise from it. People can chose not to pay with third-party merchants and just use straight transfer.
You also have a valid point. But on the other hand, having third part processors negates some advantages Bitcoins have, such as no chargeback...
True, but the payment processors would probably insure against this if it happened. I also don't think double-spending is such a big issue, as long as you get one confirmation you should be able to accept that it's a done deal.