Re-entry permit expired, need help applying at US Consulate in Lima with SB1 / DS230

[Theolonious]

My father is a legal US resident and was trapped in Peru after the COVID lockdown. His original return flight was cancelled and the airports were locked down for several months. Now, his re-entry permit has expired and we have been told that he needs to apply at the US Embassy in Lima for an SB-1 returning resident visa, or he won't be allowed back into the US. But not only that, we were told that IF the SB1 is approved he then has to re-apply for regular immigration via a DS 230 application. (1) How long does this take usually (2) What do we need to do and/or avoid to increase our odds of success, and (3)how is this any different from starting all over again and applying for a new green card? Thank you! -Theo