1) It can take several months for the IRS computers to get sync'd with the new SS Name & number. IF your first e-file is rejected for a name-SSN mismatch, you may need to change your last name to the former one first, and use that...or just keep it with the new name try again 4-weeks later....(up to ~1 April.)
2) When doing a MFJ tax return, where both of you have your own Online accounts, or both were using Desktop...or a mix.....only one person's prior-year tax file can be transferred into the new year's forms, and the other person's information must be added manually from their prior-year printout (usually not much important transfers, unless one person is self-employed or owns rental apartments or depreciating assets). Whichever person's prior year forms you choose to transfer., that person must be always listed as the First person (Taxpayer) on that new MFJ tax return. You cannot switch the Taxpayer/Spouse positions it later.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*