Here are current best answers to the questions above.

1) What cryptographic algorithm was used?  This should consider data in motion versus data at rest.

See attached document that covers the certificates and how they encrypt the data throughout the environment. 
It is from v3.1 but recently confirmed with Engineering that it is still accurate. 
(There is a Document Enhancement Request to update this to current versions 6.x)

2) Is there encryption key rotation or digital certificate renew in place? If yes, how often? 

No, Keys are generated at install and will have to be replaced manually. 

3) What’s the encryption key length if symmetric key or asymmetric key is used?

The keys created at startup are 4096 bit RSA.

4) Does the encryption generation comply with X.509 standards and produce x.509 compliant keys?

        Yes.