(1) Yes, zakah is wajib on capital amount i.e. on 96000.
(2) Zakah is wajib on capital amount. Is zakah on profit or not, we shall have a say about it when it is known that the profit is halal or haram.
(3) If you have not gifted that plot to your child as well as you have bought that plot with the intention of selling, then zakah shall be wajib on the price of plot. And if you did not make any intention at the time of buying the plot or you indented that the plot shall remain in your possession and if sometime you get benefit you shall sell it, in this case there is no zakah on that plot. Likewise, if you have gifted that plot to your child and you have kept it in your possession as wali (guardian) then too zakah shall not be wajib on this plot because there is no zakah on the property of a minor.
(4) If you buy these plots with the intention of selling, then zakah shall be wajib on their price.
(5) Most of the companies only claim that their procedure is Shariah compliant but in the real sense of term, they do not deal as per the Shariah. Hence, instead of investing in such companies, a man should do business by himself on the mode of Shirkah (partnership), Muzarabah or general business.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband