What is the ruling on a construction engineer taking a fee for estimating the cost of finishing a house for a loan applicant from the bank? And is it permissible to give Zakat al-Fitr to the wife's orphaned, poor sister who is afflicted with cancer?

The aforementioned loan has two scenarios: If it is a good loan, meaning without interest, then there is no harm in it and no harm in preparing the report. However, if it is an interest-based (usurious) loan, then preparing the report is a form of assisting in usury. If your wife's sister is in need, she is eligible to receive from Zakat al-Fitr and general charity.