2020 TT Business: Filing Amended 1120-S to IRS

My original e-file submission was accepted by the IRS; I have not yet submitted my state return (IN).  The Federal return contains an error.  Now, I have completed the amended Federal Tax Return process in TT, saved it to a different file name, and printed the forms that must be filed.   Two concerns:

1.  When I attempt to e-file the amended IRS return, TT indicates it must be filed by mail (USPS).   However, no mailing address is provided on the filing instructions page.

   Q1.  Where can I find the correct mailing address for my business location (IN)?

2.  None of the printed forms indicate that I am filing an amended return.

   Q2.  Is this OK?  If so, how do I communicate to the IRS, that I am submitting an amended return?

            If NOK, how do I correct in TT Business?