Bank loan Case Study task 1 handling null values

In Bank Loan Case Study do we have to find missing values in both application and previous application because in the important notes for project 6 its wriiten that treat only application csv with missing values also for handling the missing values to impute with mean medain or mode i should check with outliers but i am having ms excel 2013 where i didnt have inbuilt boxplot option so can i do it in pandas as they are many columns to handle the missing values i will use manual box plot method only for task 2 outlier detection