Zakaat

Calculating the value of gold for previous years' unpaid zakaat

Q: I wanted to ask some things related to the payment of zakaat. They are as follows: 

I was unaware that I had enough gold previously and now I have to pay zakaat for the last 2.5 years. So will the zakaat of each year be calculated according to the gold value in that year, or according to the current year's gold value? 

If I won't pay it all at once, and do it in installments will I be sinful in delaying it further?

Giving zakaat to one's brother in law

Q: Is my brother in law a recipient of zakaat? 

My sister and her husband have a few debts but at the same time they have a TV and phones and Alhamdulillah food in their home, water and electricity, and a nice home to live in even though it is on rent. 

We feel it will be incorrect to give zakaat to them because they are not termed under masakeen, poor or destitute but they do have debts to finish off.

My brother in law has recently opened his own business and slowly getting onto his feet.

Donating to an organization that supports Shias

Q: I sponsor a Hifz Orfan which means I sponsor a child to become a Hafiz and to get an education and to have healthy meals throughout the day but the charity I do it through which is called Penny Appeal has links to Shia Islam. 

I googled Penny Appeal and it says 'Penny Appeal is a non-denominational international humanitarian organization and does not identify as exclusively Shia or Sunni'. It also says 'Penny Appeal serves beneficiaries from all backgrounds regardless of religious affiliation'. So the children I sponsor could be Shia or Sunni or they could be Shia when they hit puberty. So what shall I do? Shall I cancel the donation or keep it going?