It should be big enough for them to move around, stretch out, and/or curl up.
Edit: To expand on the previous answer - It should be at least the length of the adult snake, and a minimum of half the adult snake's length front to back. You should also take into account any height requirements for arboreal species.
Yes it is healthy for them.
No you cannot house 2 adult corn snakes in one cage if you want to know why you can try it but I advise you do not.
nope! unless you have a peice of glass in between
Yes they like sticks in their cage but you should get them from a pet store or disinfect the sticks in some way if you get them from outside.
only one ...... if putting more snakes in same cage chance of getting diseases is more,..............
no because they will get distressed but if the tank is big enough yes but feed them separately .
Heat lamps in captivity can harm corn snakes if they are placed where the snake can get very close to it. To prevent this a wire mesh cage should be placed around the lamp
You should feed a corn snake in a separate container because, they will know that their cage isn't food and they are less likely to bite. And yes you should 100% yes if you have two in the same cage because if two snakes get in a fight over a mouse it could be a fight to the death and it isn't fun trying to pull two hungry fighting snakes away from each other.
Whether or not you can keep them both alive in the same cage may have a different answer.
I wouldn't. With most snakes, if you try to co-exist them in a tak it may result in canabalism and is not advisable.
About once a week.
no dey cant