Calories alone do not produce muscle. You should have a good balanced diet, a protein shake or two per day, glutamine is good, creatine, and a good free weight exercise routine.
You don't gain calories from sitting. You gain calories from eating.
If you gain muscle while exercising, you can gain weight, otherwise it is pretty hard to, unless you are eating too much fatty foods or too many calories.
A weight gain calculator is useful in determining how many calories you need to intake on a daily basis in order to gain "good" weight and build muscle.
6000
To gain one pound is 3,500 calories.
10
Run many miles.
Maybe 1500.maybe less like,1200
2000
The short answer is 7700 extra calories will make you gain 1kg of fat
400 calories
About 700 usable calories.