بسم الله الرحمن الرحيم
(1) Yes, it is wajib.
(2) When you are weak financially then you should take share in a big animal. The qurbani of goat is not necessary.
(3) If the gold or silver is equal to nisab then qurbani and zakah shall be wajib on the person. And if both the things are less than nisab then if the value of both is equal to silver nisab then zakah shall be wajib on their total price and qurbani shall also be wajib on such person. And if he has only one thing gold or silver and it is less than nisab but cash or business goods is available and the total reaches to silver nisab then too zakah and qurbani shall be wajib. In short, if only gold is available then the gold nisab shall be considered and in rest of the cases only the silver nisab shall be considered.
Allah knows Best!
Darul Uloom Deoband