Leaving behind in the estate a house built on waqf land

Q: My Mother passed away leaving behind a house on a Waqf land which she rented. The land is such that we rent it for R5000 per annum. Then we have the option of building whatever we want. Now that she passed away leaving behind 3 sons and her husband. Will the house form part of her estate or not? 

Please provide references from the Hanafi Mazhab as one of the brothers is very adamant on following the Hanafi Fiqh. 

Some other Mufti mentioned that in Hanafi Fiqh, such a house built on this kind of Waqf land will not form part of the estate as such, rather the value of the house in the form of rubbles will be calculated or something like that.

Wife discharging zakaat on her gold for previous years

Q: I have been married around 15 years, and my wife was give more gold ornaments by their parents! There is zakaat to be given for it and she did not provide it! I don't have any gold or savings! Only my wife's gold! How can I calculate the zakaat for the past 15 years => Gold price was low to high till now. Do I need to calculate the yearly gold rate on that year! Can tell me how to discharge the zakaat for the past years?

Distributing the land in inheritance when one heir built a structure on it

Q: I built on my mother's property with her permission, my sibling doesn't want to compensate me for the improvements. She say that I occupied it for free for many years. 

My Mother is late. I have one sibling (sister) we and are heirs to the property. 

What is the Islamic ruling on this? Does she have a claim on the building that I erected with my funds and the proceeds that come from it or does she have a claim only for the land that the building was erected on?