The more fingers in the pie, the higher the cost. At least that's my guess. I imagine more expensive labour and tighter regulations also greatly increase costs.
Without such funds nothing would get done at all.
No, I don't think that. But I do think it's likely that the various levels of US government like to stake their claim to more autonomy compared to the various levels of government in Europe (particularly at the local level -- I'm sure the EU and national governments love to "get involved").