treppenwitz

The rule is within 10 days

Yes:
The above thread speaks for itself.

Can be updated at the embassy or even at the port of entry 

Bear in mind if she accumulates more than 6 months of presence in the US per year she will become of interest to the IRS.

Admittance on a K-1 is based on the intent to marry within 90 days. There is no provision in the INA nor Field Manual that AOS must be submitted within a certain time period.
CBP denying @Abbey B entry for 15 day-overstay is not realistic. The above is fear mongering.

K-1 is allowed dual intent. And all AOS applicants have authorized stay allowed by the US Attorney General.
Technically true because of INA Section 237(a)(1)(C). But in reality, ICE does not start deportation procedings for K-1 overstays.
@Abbey B only overstayed 15 days.
USCIS also issues AP to TPS beneficiaries. Some overstayed for 8+ years before getting TPS. All of them have re-entered with AP without issue. [Side note: After entry with AP, TPS individuals that initially Entered Without Inspection are then eligible to AOS; this is a known loophole.]
AP travel is routine. They see it frequently.

With approved Advance Parole that is not an issue; don't worry. Also, after the I-94 expires AOS applicants have authorized stay allowed by the US Attorney General.

Correct. The form is flawed regarding this.
First time I've seen it. Seems they (very) wrongly assumed the beneficiary only had a Canadian tourist visa. Most embassies are strict regarding beneficiary's status in the embassy's jurisdiction.

Biometrics is generally within 60 days of AOS packet sent in (NOA1) . Still timeline is 4-5 months about total from NOA1.. Can vary a little bit but that's still general timeline.

I think you have to call the USCIS contact center to schedule an appointment:
https://www.uscis.gov/about-us/find-uscis-office/field-offices/florida-tampa-field-office
 
I was told you can still get appointments but they've changed how you can book it because the system was being misused by people that didn't need appointments. You should be able to get an appointment at Tampa. 

The name of the spouse visa is IR1 or CR1 depending on the length of your marriage but the paperwork to get it is the same, so it is commonly called IR1/CR1 on the forums. You have been married more than two years so yours will be IR1 visa. 
 
Yes, Direct Consular Filing means your initial petition paperwork for the IR1/CR1 visa starts at the USCIS office in London then transfers to the Immigrant Visa Unit in London for the interview and visa issuing part. 
 
Regular IR1/CR1 visa processing has the same paperwork but to different places--
Starts at USCIS in the states, then to National Visa Center (NVC) in the states, then to Immigrant Visa Unit in London.
 
 
 
 
 
 

Just keep them as they are now.  My mother had an same issue very long time ago, she made an infopass, USCIS told her no issue ( and this was the time they did not place Visa stamp/1 year temporary on passport like they are doing now).  No issue happened and my mother just got her English name when she got her USC.

Yes, it's as simple as an I-130, a medical, and an interview. 
 
Since this would be for an IR-1 immigrant visa, he would immediately become a permanent resident upon entering the US, with the ability to work and travel from day 1.
 
The plastic green card would appear in the mail a couple of months after entry. 
 
Keep in mind that an immigrant visa is valid for around six months upon issuance (technically six months from the date of the medical), so if he had a medical in, say, November, once issued his visa would be valid for his initial entry to the US until May 2020. And he could always just activate it by entering, then turn around and leave again for up to around a year to close up his UK affairs before his LPR status in the US would be threatened. 

Do you remember doing an I-134 Affidavit of Support for the K1 interview? Well for the spouse visas (IR1/Cr1) interview,  the Affidavit of Support is a different form called I-864. It is stricter and has more requirements written in immigration law. One is the sponsor must be a US person...live in the US...domiciled in the US.  Since you are the spouse, you are the primary sponsor on that I-864. But not living (domiciled) in the US, you don't qualify to be a sponsor. Catch 22. 
 
The work around is prove your time in London was temporary and you maintained your US domicile by showing you kept up your driver license, voter registration, have a US bank account and such as that. Or if not,  you can show "intent to restablish domicile" which is pretty easy for a London interview.  Correspondence looking for jobs, a job offer, or checking out apartments for example. Maybe an affidavit from your folks stating you will be living with them if that's the case. You will need a joint sponsor on the I-864 because you will not have US income for your I-864. OR you can file DCF while legally in the U.K., then move ahead of him and start a job. That takes care of domicile and income, but is probably not realistic on your timetable.

You could ask one of your congressional representatives to enquire on your behalf to see what's going on. That might get something happening.

When the time comes, make sure she informs the IO at the beginning of her interview that she needs to update the travel history on her application to include the time abroad after filing.

A photocopy of the I-130 receipt notice is sent in with the I-485 packet.

You are this close.  Let the consular process complete as it is the fastest way to green card for her based on your circumstances 

You would need to be a US citizen before you can even start the K-1 (fiancee visa) process.
The K-1 visa process is taking only a few months less than the spousal visa process. The 2-3 months you heard of has not been accurate for a couple years now. There have been short periods where ~3 months start to finish was possible, but expect 8+ months on the low side now.
There's virtually no way the fiancee visa process would be faster even if you could apply for naturalization today.

Not an issue: http://www.cic.gc.ca/english/visit/visas.asp
I assume OP would travel by land (or water).

Moofy lives in Bellingham, WA, not Reno, NV. Vancouver, BC is an 80 minute drive from Bellingham. San Francisco is a 15 hour drive (if they don't stop along the way) from Bellingham.

I-539 extension? High odds that would be denied, IMO.
The F2A process takes about 2 years. She must leave the US before the I-94 expires. As a tourist, she should spend more time outside the US than inside.
F2A not IR-1/CR-1

AOS-based EAD/Advance Parole combo card* is free. Even if you don't have travel plans I recommend to submit Form I-131 with Form I-765 and the photocopy of your I-485 receipt notice.
*EAD/AP cards say the following:

It can be done online: https://egov.uscis.gov/e-Request/Intro.do "Typographic Error"

If you're referring to chats and call logs, then screenshot them and print them out. I can't say they will put a whole lot of merit into them, but that is what most people do.
Both USCIS and the embassies/consulates will not consider evidence directly on electronic media (even CDs/DVDs). It needs to be in some form of physical document.