M+L

Just want to relay NVC's reply here in case others are curious in the future: (I did an online enquiry asking for more time)
 
"To Whom it Concerns:
 
Thank you for contacting the National Visa Center (NVC). To keep your case active, do not let more than one year go by without contacting the NVC.
 
The easiest way to keep your case active is to access the Consular Electronic Center (CEAC) at https://ceac.state.gov/iv. Every time you go into your CEAC account, it will update the last contact date."

Just want to relay NVC's reply here in case others are curious in the future: (I did an online enquiry asking for more time)
 
"To Whom it Concerns:
 
Thank you for contacting the National Visa Center (NVC). To keep your case active, do not let more than one year go by without contacting the NVC.
 
The easiest way to keep your case active is to access the Consular Electronic Center (CEAC) at https://ceac.state.gov/iv. Every time you go into your CEAC account, it will update the last contact date."

If I may chime in..
For IR ( spouse , child or parent of USC), it is sufficient to do
an ASK NVC inquiry saying “ I need additional time  due to unforeseen circumstances “. Do it every 11 months from the most recent contact 
 
This will generate an automatic confirmation email and serve as proof of yearly contact…
 
For any preference categories ( ex F-2 A , F-2 B or ..) completing the DS-260 needs to be done to secure priority date .
 
I realize they prefer log in only ..but since the system has historically been plagued with issues , the ASK NVC is an easy solution to create an instant record of contact
 

 
 
 

At the time I uploaded the DS 260, I did not know much, so I just uploaded it in order to have some activity.  Later, I uploaded some things, then deleted them, for some activity.  They won't  do anything with anything until you do the submission.
 
Your second post was confirmed by an e-mail to NVC.  A login is apparently sufficient.  I keep a "login log" and check it once in a while.

Enter date of spouse's death.
 

No, do not leave them out.  Enter the parent information that the form asks.  For the questions about parent's current residence, enter "Not Applicable - Deceased" or simply "Deceased".