When I Love

According to NVC there working on cases submitted in July but that can also vary. Recently I've seen cases DQ'd in days.
https://travel.state.gov/content/travel/en/us-visas/immigrate/nvc-timeframes.html
 
After DQ it's taking about 1.5 month to get an interview for CR1/IR1 in Morocco and about 2-3 months for K1.

According to NVC there working on cases submitted in July but that can also vary. Recently I've seen cases DQ'd in days.
https://travel.state.gov/content/travel/en/us-visas/immigrate/nvc-timeframes.html
 
After DQ it's taking about 1.5 month to get an interview for CR1/IR1 in Morocco and about 2-3 months for K1.

Definitely add the Joint Sponsor at this point. With Casa, you don't want to leave anything out for review at the interview. You don't want to give them any opportunity to place you in AP. Casa does accept joint sponsors however it's frowned upon and combined with other red flags can cause AP. 

There's no right or wrong with going color or black and white. I would want the CO to have a clear picture in my evidence. Therefore I would choose color pictures. The background paper or ink doesn't matter. 

You can under "other. 

The updates you see on your account are typical. That means someone viewed or worked on your file. The downside is that it changes nothing. The updates let you know your file is not forgotten. AP has no timeframe so there's no telling when your case will be processed. I would recommend to submit a Congressional Inquiry if you've been waiting for 3 months or more, though one can be done at any time. There's nothing to do but wait for the Consulate to make a decision or give further instructions. Calling and emailing will go without answer. 
 
https://www.facebook.com/groups/258071455346524/?ref=share

Your question is not quite clear.
 
The USCIS and NVC stage appear to be moving faster than usual. However the consulate is still closed therefore you'll get stuck at the interview stage. In addition, the consulate will have to catch up on backed up interviews once they open. It was taking about 5 weeks for CR1 to get an interview before and 3 months for K1. There's no telling how long it'll be once they reopen. 

Only a second car or equity in a second home would be helpful.  It's "liquid" assets that improve the financial picture in this context.  Check USCIS's definition of "liquid".  Consular officers use the same definition.  Primary residence and only car are meaningless in THIS context.

The applicant is always the sponsor and will complete I-864. 
The sister will be the Joint Sponsor and complete an I-864 if she lives outside the applicants home. If the Joint Sponsor is married and files Joint with her spouse, her spouse will complete I-864a.
 
Sponsor:
I-864
Tax Return and W-2 or Tax Transcript for most recent tax year.
 
Joint Sponsor and Spouse:
I-864
I-864a
Tax Return and W-2 or Tax Transcript for most recent tax year.
Evidence of Legal Status of Joint Sponsor
 

Let's not confuse people further by using the wrong terminology.  There are no "co-sponsors" in immigrant visa cases.  The sister will be a "Joint Sponsor".  If the sister is married, her spouse will be the joint sponsor's household member and provide an I-864a.