Not necessarily. Depending on your weight and how often you do them it will vary for each person. If you have been doing them for a long time and cant do 25-50 without feeling winded you should see you doctor.
No
you cant. but you can get abs by doing bicycle crunches and regular crunches.
yes they can.
Yes, doing crunches will help with the overall conditioning of your body core - which is part of the driving force needed by your legs,
20 calories per 100 crunches, if you're doing them correctly.
By doing exercise and crunches
No, you will tone that specific area but you can not 'spot' lose weight by simly doing cruches. By doing crunches you may lose weight from any part of your body.
Doing crunches won't make you bloated, it will help burn belly fat and gain abs. Eating junk food will make you bloated and fat.
Doing crunches does not make you skinny. Eating less calories than you burn and being active (cardio exercise) will make you skinny.
doing crunches makes muscle on top of fat and after that its almost impossible to lose that fat!
You need to hold your stomach in when doing crunches. If you push your stomach out the muscle will shape that way.
How much weight you can lose in a month by drinking water and doing crunches every night also depends upon other factors. These include you start weight, gender, age, diet, metabolism and how many crunches you do each night.