If you're booking a rental for the US on a international Hertz website, it should include insurance (but you should see it in your confirmation as well).

As for ski-pass throughs, these can be hit or miss with any of the carriers, it all depends on the vehicle equipment level, which can vary even in each class. The few times I've had to rent a run of the mill car (mostly rent Prestige), I've had them with split folding rear seats (one section folds down seperate from the rest) and without.