Write a SQL statement to retrieve all columns from employees table with last name of 'abel', regardless whether the letters are in upper or lower cases.

Write a SQL statement using employees table to display the first name column in all capital letters, the last name column in all small letters, and email column with its first letter capitalized.

Write a SQL statement using employees table to display a derived column with first name and last name concatenated, a derived column with only the first $3$ letters of first name, and a derived column with the length of first name.