When present in the place of congregational prayer, one can recite Takbeeratul-Ihram - even if not close to the group of the congregation - and walk even during prostration to join the congregation.
It is prohibited to draft or write the contract for the loan agreement that involves interest or to do anything that is related to it, like calculating the balance of what the client owes. It is permissible to work in determining the eligibility of the customer to take the loan.