HANA AWS instance- few queries

I have few queries about HANA instance on AWS.

> How do I check which version of HANA is installed on AWS?

> Everytime I stop and and start my instance HANA studio says "some services are not started". In order to resolve the issue I have to restart HDB via ssh console. Is it normal?

> Can I change root and hdbadm password without causing any issue with instance?

Thanks

Angad