Calculating zakaat on a rate that is more beneficial for the poor

Q: We are having an economic meltdown in our country. Due to lack of forex reserves, there is a vast difference between the dollar in the bank and the dollar on the black market. Due to scarcity, majority of the people are dealing with the black market rate which is very high in comparison to the bank rate. The bank also sometimes charges a premium that brings it close to the black market rate. The whole economy is running on the dollar and things change according to the rate. 

The issue comes about when calculating zakaat and other financials. Some Ulamaa have taken what they call a middle rate to benefit the masses. Others are taking the bank rates. Yet still some are of the opinion that the black rate should be taken into consideration because everyone is using it. What should be done in this case? What rate should we use? Your advice will be greatly appreciated.

Missing salaah due to shopping

Q: If a woman is out with her family to a hotel to eat and went to a mall to enjoy some time... So what must she  do if salah time is due? She prayed asr at home and went outand now it's maghrib time and she can't pray because there is no women's prayer room in the malls or hotels... So what must she do in this situation?

If she does jama' salah in her home, like praying 4 rakah of asr and then 3 rakah of maghrib in the same time because she won't get a place to pray maghrib, is this correct?

Using one's fathers money without his permission to start a business

Q: My father keeps his money in my bank account, which mainly comes from monthly shop rent approximately 14 lakhs in total till now. 

I used 1.5 lakhs rupees out of those 14 lakhs without my father's permission and started a business which was pretty successful. After a couple of months I put the amount back. 

So my question is that the profit that I earned, is it halaal or haraam and should I continue this business?