Bank Loan Project Doubt

I'm currently in Bank Loan case study. I don;t understand how to start this project. Unlike the previous projects, there are 122 different column headers and so there are so much blank spaces for different column. Please guide me in how I can clean the data given the huge dataset and how to treat the blank spaces. Also for which columns should I find outliers. It is not possible to apply Quartile rule to identify outliers for every column, so how can I find out the outliers which are to be necessarily considered. Please help me in how to begin this project and how to follow on with this project. At last please tell me how should I use the previous application dataset with the current dataset? Thank You