Do we have to pay zakaat on the house in which we are living?

My dad passed away few days back. He left some property and valuables which my family (mother, brother and sisters) do not want to distribute for the time being. Now, how do we calculate zakaat on the property since the purchase price is known but the market price varies.

Do we have to pay zakaat on the house in which we are living?

My dad's office is still open but no major work is taking place since my dad was in a partnership with my uncle and he had given all his business (not office) to him and my uncle is working from there. I used to visit the office on a daily basis for a few minutes and then left for my office. So, do we have to pay zakaat on it also?

We are using my dad's cars and other belongings of my dad, do we have to pay zakaat on these items and what value?

Also, we are giving charity from his belongings but which has more reward, sadaqah or khairaat?