Hajj on loan

My father is a shop-owner. As a normal procedure in every business he pays the suppliers in installments. This is an on-going business and balances are cleared in due time as per mutual understanding.Question 1) In order to perform Hajj does he need to clear all the pending installments to make his Hajj valid? Does it come under the category of loan?Question 2) What if he forgets paying some real loan or installment (such as above) and remembers it during or after the performance of Hajj?Pls. guide in the light of Quran and Sunnah.