Hi KA,
I don´t think you can direct create PPM in SNP. At least OSS Note 1079959 confirms my thought:
Functionalities supported by PDS and not PPM
Engineering change management
Differing from the PPM for SNP, the PDS for SNP is transferred directly from ERP and is not generated from the PP/DS-PDS.
For you second point, please refer this thread:
Kind Regards,
Mariano