US Immigration from Taiwan

Dear VJers,

My husband (USC) has been overseas for 18 years. We flew to the states this year on July 1st due to some family issues. I started my green card application in Aug, but first he had to catch up his 2016~2019 tax returns so that we can have tax transcripts that USCIS asked. We knew the tax transcripts might still be unavailable when I filed, but we sent the tax forms out anyway. Today, we realized we submitted the wrong forms for overseas earned income exemption (I know, it's been a while since last he did it), so we need to re-file it again, but we have some questions:

1. For 2016~2019, If we are in the states 2020 to file 2016~2019 overseas earn income (married filed separately), should we use foreign address or US address as filing address? Which IRS office should we send to? Can we resubmit all files or just update the ones we missed?

2. For 2020 tax, since we have 182 days overseas, 184 days in USA, are we still qualified for foreign earned income exclusion for 6 months? Should we attach Form 2555 and schedule 1 as well?

3. Since I am still waiting for my green card, I don't have a SSN and I don't have a job. For 2020 tax return, we are thinking married filed jointly. We will submit W7 for my ITIN along with other tax forms.

Thanks for your great help,

Stay safe.