Stuff like this is actually pretty easy to do, with regard to the electronics portion. If you're building a new house or doing some fairly significant renovations, then you can do this kind of stuff with a fairly minor increase to the total cost. Now if you want to retrofit an existing house or apartment with these sorts of features, that is a major PIA! It's like adding structured ethernet to an old house... you can do it, but it's very time consuming, and it never turns out exactly like you want it.