Need help setting up home theater

Well, this may be a lot to take in, but this is the scenario.

We have an old sony DVD amplifier that we bought back in 2008, which is on the verge of breathing its last, and I might as well use the 5.1 speaker system that works fine (I have tested on other sources).
We have a three story house, the TV being fixed in the 1st floor and the current sony dvd player being in the second floor. We don't watch TV a lot, so it'd be better if the a/v receiver which we'll buy during upgrading remains in the second floor, as we hear a lot of music and we primarily inhabit in the second floor. But if there is a way to keep the av receiver in the 1st floor with the TV, and maybe find a way to have 7.2 surround sound in the 2nd floor, it'd be best.

I will use the existing speaker system in my bedroom with a separate receiver that I will buy sometime in the future.

What should be the most effective way to do it?
I know I have been vague in a lot of places, but it'd be best if I can clarify my questions based on what you ask, rather than taking the hassle of explaining everything at once, and failing miserably.