1 - Getting optional in ESTF pugs is relatively easy, provided players work as a team on well documented "default" plans, and react as opportunities present themselves.
2 - Grinding STF's for Dil & Omega Marks is definitely all about " more & faster "
3 - Most pugs are successful at optional, I'd estimate 90% minimum.
4 - The only reason NOT to care about Optional, ( 25% Omega Bonus ) is if a player doesn't do enough ESTF's to have it make a difference.
As for the private STF rooms from one of the channels, I DO expect the match originator to dispel any vagueness, and help set the roles for a better result.