2) Higher cab fares during night time so that drivers have incentives to operate during night, especially, on friday and saturday nights.
3) Lower medical/insurance costs
What? You're going to incentivize driving over taking a cab? At least in NYC, this is a huge mistake.
Incentivize biking for everyone and good public transit. If you're going to think about fixing transit, stop thinking about cars in the first place.
There's an idea - Bar Van, free rides home from the bar, completely funded by advertising from area businesses that want to support "don't drink and drive" initiatives.
"Oh crap, I have a late movie sitting here collecting fines. I'll just order another pizza so they'll pick it up..."
The idea is well intentioned, but what kind of liability do you think private companies would get from putting a bunch of drunk people in a crowded van at 2AM on a weekend? I think it would have to be a state sponsored thing for it to work.
Maybe there's no legal liability for Bob's Bakery in a situation like that, but it is certainly bad for business.