difference in surname

Hello, I would appreciate if someone can advise me how to proceed and file the visa. My name on all the educational documents is "Sumit Kumar" whereas my passport and professional (work) documents have "Sumit Kumar Sharma". Will this be an issue while filing the visa? There were no issues...

Today, at last, I got a copy of my birth certificate from the government website. But, it was having my name as Dileep S, where "S" is the initial for Sankar, which is my surname, as in my passport. Now, I am worried whether that will make it necessary for me to get an affidavit if am providing...