If I had a premmie baby, I would use pasturised EBM, as I know that it is well screened and safe.
I would not use EBM from friends, although I would from my sisiter. In fact my sis is preg atm. I would feed her baby if she needed a feed and was with me, althouhg only if my sis said yes. I would also let her feed my baby. I wouldn't let anyone else, just her though. We are very close and she is a non drinker/smoker just like me.