So what happens is you email the consular to ask for DCF processing (aka I-130 acceptance in exigent circumstances, employment change for example), they say ok and tell you to come see them (with or without your new spouse) - you come with completed forms and form of payment and once you have the approval (could be verbal on the spot like we had decades ago, could be via email as it seems to be the norm these days), they'll email you and beneficiary for next steps - DS-260, Affidavit of support, paperwork from beneficiary (medical exam, birth certificate, marriage certificate, any divorce certificate(s), police and court certificates... before they schedule the interview - this all could take couple of months but after approval you don't need to remain in the country, you can head to the US.
Don't know about job loss (hopefully doesn't happen), I imagine the process would still go on but you'd need a joint sponsor?