To convert PKCS#p12 file to a PEM file, use:
openssl pkcs12 -in cert.p12 -out cert.pem -nodes -clcerts
Now you will have both the certificate and key in the cert.pem file without a password.
If you need the certificate and key in separate files, use this:
openssl pkcs12 -in cert.p12 -out cert.pem -clcerts -nokeys openssl pkcs12 -in cert.p12 -out key.pem -nocerts -nodes