Perform the following tasks using MongoDB queries: List only the first 20 names of companies founded after the year 2010, ordered alphabetically. List only the first 20 names of companies with offices in either California or Texas, ordered by the number of employees and sorted largest to smallest. Provide screenshots of your statements and the results as evidence. Design and implement a MongoDB aggregation pipeline to show the total number of employees by state for all companies that have offices in the United States.