Does your business name need to be the IRS "Name Control" from the EIN and can you mix 1099s that have your SSN and EINs on the same return?

Just got an EIN and confused about the "Name Control". On W9s aren't you supposed to use the full legal name? If so when is the EIN name control used when filing electronically? As the actual business name on the tax return?

From the letter,

Your name control associated with this EIN is ----. You will need to provide this information, along with your EIN, if you file your returns electronically.

Also if you have a business and are already getting paid with income reported on 1099s using your SSN, can you mix those with 1099s using your EIN?

Thanks