If I am not holding with the minyan, when do I say “Keil Erech Apayim”, before Pesicha or after “Vaanachnu Lo Neida”? Same question is regarding “Ata Horeisa” and “Vaani Sefilosi”.
They should all be said at the appropriate place during Davening, not specifically with the Minyan. Sources: ראה מג"א קלד סק"א: ואומרים אל ארך אפים מעומד מפני שיש…