Earning interest to pay off an interest bearing loan

Q: I have a brother and a sister. My brother has taken a loan from a bank and has to pay back the loan with interest. My sister wants to open a fixed deposit with the intention of giving the interest earned on the fixed deposit to my brother so he can pay off his own loan. Can she do it, even when my brother has enough income to pay off the loan himself?

Using someone else's student card to get a discount

Q: I currently live in Pretoria and work in Jet Park (I travel about 128km a day to and from work). Currently I use my car everyday to work and back. I have previously looked at the Gautrain as an alternative, however it worked out a little too expensive for me.

Recently, my small brother informed me that he receives a discount on his Gautrain trips (as he is a student) but doesn't use this discount as his campus isn't so far and it's easier for him to drive. As he isn't using this discount- He had offered it to me to use his discount to travel to work.

My question - Would it be permissible to use his discount for my benefit (considering he is a student and I am not)?

Old lady going for umrah during iddat

Q: My grandmother has an umrah trip planned for end of March. But her husband passed away a few days ago (Feb 11). I am aware that iddat is for 4 months ten days but my grandma is 75 years old and I wanted to know if she is able to go to umrah and complete the remainder of her iddat when she gets back or is it not permissible for her to go? I was not aware if age makes a difference.