Answer
(Fatwa: 2271/1867=B/1429)
(1) One will have to evaluate gold and silver as per the market rate at the time of zakah, it is not right to calculate it by deducting 10%.
(2) If you sold it and the amount came in your possession, then you will have to pay its zakah at the time of paying the zakah of other money you have after passing one year.
(3) Yes, it is necessary provided the counting is possible.
(4) Whether it is the income from house or shop or it is salary, if it reaches to nisab (the amount prescribed liable for zakah), then it is obligatory for one to give its fortieth part as zakah.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband