Because the hoodwork for PP is not "instrument flight training" (see 61.109), it may be given by a CFI without a CFI-I rating. Also, because it is not "instrument flight training," it doesn't count towards the 15 hours regardless of the qualifications of the instructor who gave it.
Legally, no. The safety pilot requires a medical because the safety pilot is exercising a Private Pilot privilege (see 91.109(b)) and thus must hold a medical valid at Third Class or higher (61.23(a)(3)(i)). The issue of whether or not the safety pilot is acting as PIC or SIC or neither is irrelevant.