1. What kind of house do you live in?
2. What kinds of houses do you live in?
3. What kind of houses do you live in?
[#1 and #2 seems to be correct. What about #3? Here the singular noun 'kind' is used. Is this one correct?]
1 is correct when speaking to one person or a family.
2 is correct when speaking to two or more people who are probably not related -- or perhaps someone who is wealthy and has multiple houses!
3 is correct when speaking to someone who has more than one house. This sentence is quite awkward, though. I have never heard or read this sentence structure before.