Not a lot really.
Let's say you're doing 9 MPH, which should be real easy if you're staying on a decent road. That'll mean that you're done in 20 minutes, tops. And at that level of effort, you're maybeable to use up 450 cals/hour, which would put your burn at 150 calories or something like that.
It's about 1/3 of a cupcake's worth of calories.
Riding a bike is good for your cardio and will give you great legs. It may help you gain a flat stomach as well depending on how long you ride and how fast.
Depends on how hard you ride. If you're only pootling around - not many. If you're getting sweaty and winded, as much as 400.
The degree of resistence will determine how much. You would have to account for your weight, the weight of the bike, the surface you're riding on, the material, density and texture of the tires you're riding on, the angle of the surface you're riding on...It's subjective, so has no one right answer.
about 50-60 psi for uphill riding
Chemistry has been involved in the production of pretty much every part of the bike. All from the paint to refining the metals the bike is made of.
Ice is slippery, right?
I don't think it will do much except flatten the grass and kill it.
Pretty much all of them.
67 miles
A bike can travel the full 12 miles depending on the endurance of the rider.
None, its a bike. Only vehicles that burn fossil fuel release carbon dioxide.
Depends entirely on how much riding the person does, and what the person would have done otherwise. If the person is riding a bicylce instread of using an motorized vehicle, then some CO2 will be saved. If the person is riding instead of walking, then there's no difference.