vibgyor1111

Coming in at the wrong time I've spent about an hour and a half in the queue at SFO just after they changed so that all e-passport holders went through (US citizens or not) the same line, with no secondary. 
 
Then again I've gone through SFO in less than 20 mins (obviously no secondary) after getting off the plane quickly and lucking it so the prior flight arriving had almost completely cleared the queue.

My wife had 3 hours in Miami and just barely caught her connecting flight after running to the gate. She was almost 2 hrs in secondary so that was out of the ordinary.

One POE can vary hugely throughout the day depending on time of day, number of flights arriving etc.
 
bear in mind that apart from immigration, your wife will have to collect her baggage, go through customs,  recheck baggage and probably go through security again..as well as possibly changing terminals. 
 
I’d agree at least 3 hours. Rather risk an hour of surfing free WiFi than risk hassling trying to rebook a missed connection. 

There’s no way of knowing. If you have a layover flight, give it at least 3 hours. 

I think at least 4 hours is best.  Depending on how busy they are it might just take an hour but it is better to be safe and get the most time between flights.  My recollection is that she has to go thru secondary inspection the first time.
 
What POE are you arriving at?

No, not really.  It just depends on if a couple wide bodies arrived at the same time.  I like 4 hours but will take 3 if I have to.  No less, UNLESS there is a later flight to the next destination.  The issue is not so much how long the POE will take but that many incoming flights to the US leave/arrive late.

Also, AP is a catch all label, that applies between the interview and visa issue, even if all that's going on is going through the queue from interview to visa printing.

Yes, going through AP is normal. Nobody knows how long AP will  be (days, weeks, months, or years), but typically it's a matter of days to a couple weeks. It's only been 2 business days so that's fine.

both the petitioner and the co sponsor will file i-864 forms.  

Submitted docs in late July.  Notified about interview in mid August for interview on Sept 7.  Can't get here soon enough.  

The Consular Officer will understand this, so no worries.

I would let it go.  You don't mention the country.  In any of the former Soviet Union countries it is well known that there usually are multiple correct spellings when transliterating from the original Cyrillic.  The absence of a letter is pretty easily explained.  If it comes up, just give the same explanation you gave here.

It's probably OK but there's no way to be certain it will not be an issue.  With matching dates of birth on all documents, I suspect it will be OK.

Current income is current income, not year to date income.  If you don't have paycheck coming in "currently" then your income is zero.  However, note the words "that you are using....".   Even if you were still working when you submit the I-864, your income would still be stated as zero because you can't "use" it to qualify.  You can't because it won't continue from the same source back in the USA.  Become an A-Student of those I-864 instructions.  Really.  Do it.

No he did not take the I-130. There are a few repeat documents that the NVC asks for that was sent with the I-130 such as petitioners bio page of passport & marriage certificate...But the only other thing he brought that was in the I-130 packet was proof of bona fide relationship. 

I'd personally pass. The interview isn't something you can really "prep" for...they ask questions about the relationship and other factors that one would reasonably be expected to know. They may not even know the answers...they are sometimes just gauging the response to see if the applicant has a reasonable explanation. The applicant may not even know the answer to everything, and that can be fine too.
Being too "rehearsed" will likely look bad if they're trying to gauge a response.
 
I'm not sure what there is even to do to prep for the medical exam. Instructions will be listed in the packet, and many friendly VJ members can answer specific questions/concerns in the regional forums.

Consulate reviews where people give their interview experiences are very valuable.  Read these and decide if you still think further coaching is necessary.  http://www.visajourney.com/reviews/index.php?trim=no&cty=&cnty=Vietnam&page=1&dfilter=5&topic=IR-1/CR-1 Visa