for this, I put in the schwa insertion rule, as well as the voicing assimilation rule - however, I'm not sure what explains voiced alveolar nasal becoming a voiced bilabial nasal.
First, list the differences. I see three:
1. ə -- you explained that
2. ʰ -- what's going on there?
3. m -- yes, it's assimilation, but what kind? (It's a nasal, so it's...)
I'm not seeing voicing assimilation in that particular example, though.
but what could explain the voiceless alveolar fricative becoming a voiced alveolar fricative?
It isn't. It's voiced becoming voiceless. You had the answer above, just applied to the wrong data.
Since this seems like homework, I'd rather have you figure it out yourself than give away the answers. But that should get you started.