Answer
(Fatwa: 1426/1256=B)
Zakat is wajib on jewellery when you own it a complete lunar year. If you gift the jewellery to your wife before completion of one year, then zakati shall not be wajib on it. But, if you do this only to avoid zakat and in fact you do not intend to gift it to your wife then it is playing trick with Allah, thus it is very heinous and may be punishable before Him: و سببہ ای سبب افتراض الزکوۃ ملک نصاب حولی تام ای الحول القمری لا الشمسی (3/125)
(2) Yes, wife also has to give zakat of her jewellery whether she uses it or not.
(3) Aalim-ul-Gaib is one who knows everything that has occurred in past and that will occur in future. This is characteristic to Allah alone, there is none Aalim-ul-Gaib except Allah. Yes, if Allah gives knowledge of some gaib to any prophet or any servant of Him by any means then they also can have that particular knowledge.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband