A lot of International flights from Europe fly into Cancun, seems to be a popular. Now I have only been to Cancun from the US but I knew people who did the LHR route and they would not have been paying mega fees, a quick google suggests they are around $1000 return.
C would be issued for a set time not per flight usually.
B and C would require the same showing non immigrant intent issues.
You have spent a year doing something but not booked an appointment?
A foreign Consulate would be less able to review the case so more inclined to refuse. Especially if it looks like Consulate shopping.
I have always taken the view that any reputable Immigration Lawyer would refuse to take on a B case, there is nothing they can add other than their fees.
Yes I have heard about harvesting of appointment dates.
There was a thread of a similar nature not long ago, I'll link it below. The issue seems to be that from the CO's perspective, there's no difference really between a C1 and B visa so the odds of approval are more or less the same for each application. Thus it makes more sense to apply for the B, don't bother with the C1.
If the embassy or consulate is willing to take non-residents then it shouldn't be a problem. My MIL was able to get a B visa via doing the interview in Kazakhstan despite living in Russia. The embassy in Kazakhstan said they were willing to accept non-residents so she just applied there, paid the fees and booked an appointment. You would need to check with the embassy or consulate first and make absolutely sure they will take a non-resident, otherwise even if you pay the fee they won't give a refund.
It could be possible because some services appear to be using bot software to scan and book appointments. I cannot confirm that but it's what I've heard. On the flip side, these kinds of visa offices can and do scam people so be careful.
