How to file tax return if single-member LLC has EIN?

[Weng L.]

Hi

https://www.irs.gov/businesses...

According to this IRS guideline, I am supposed to use SSN to file tax return for my LLC (I am the single member of the LLC). I searched in BP and folks here said single member LLC can elect to have EIN too.

The thing is I am applying for a mortgage under LLC and lender requires EIN in order to not report the loan to my SSN. So I have 2 questions:

1) Am I allowed to apply for EIN for my LLC where LLC is a single member LLC?

2) After I have EIN on LLC, am I required to file tax return separately (separate tax returns for SSN and EIN)? or I have the option to choose to file tax return either separately or together (report everything under SSN)?