C Corporation Tax Questions - death of sole shareholder

Feb. 2021 incorporated.

Nov.  2021 death of sole shareholder/owner. All engineering services cease. All corporate function ceases to exist.

Jan. 2022 payment of 2021 invoices received.

Feb. 2022, spouse substituted in as shareholder to wind down corporation, file/pay taxes, creditors, etc.

Do I file taxes for 2021 and 2022, and file a form 966?

Can I file a tax return for 2022 NOW, or do I have to wait until the end of this year when 2022 tax forms are available?

Are C Corporation Taxes due MARCH 15TH or APRIL 15TH.