1) In Average American house in your state, how many total rooms are there ? Do you have a separate room for clothing closet like they show in movies ? or it is just a cliche ? Like this [1]
It depends on the size, when it was built, how many bedrooms/bathrooms it has, and a ton of other factors. I'd say most houses have somewhere in-between 3-10(ish). Most do not have a walk in closet, they're not super rare, but they're not the norm. If you think it's normal for Americans to have a walk in closets, it's definitely a cliche.
2) How is most of house's roof ? Is it /\ this shaped ? Or is it flat terrace which you can access ? Like this - |_|
Most will be /\, though flat terraced roofs do exist.
3) Is AC extremely common in average housing ? Or people manage with fans ? If AC is common, which one is more prevalent ? Windows AC or Split AC?
It depends on what part of the US you're talking about. In Texas or Arizona it might be common, but up in the Pacific Northwest it's not that common as we only have 10-20 days (usually, this year however was terrible) that need it.
4) How do you get fuel for cooking ? Do you buy gas bottles ? Or do you have piped gas line ?
Most people either have natural gas piped into the stove, or are electric.
5) On Average day, how do you clean your self? Do you use shower? Or take a bath in bathtub? Or just directly pour water on you from a bucket and tumbler?
Most people use a shower.
6) At what age children stops sleeping in same room as parents and get their own room ?
Somewhere in between day 1 and 5 years old. Somewhere between day 1 and being a 3 year old I'd say is when most do.