Hi Mark and thanks for your interest in MCC.
Since Mikael covered for permissions issues I will focus on remaining of your questions. Let me first say we are aware of problems and working hard on new version of MCC. Some of the changes are already available in MySQL NDB Cluster 7.6.
So to the questions.
o "Does anyone have a definitive list that confirms what modules (and all supporting modules) are needed for python for the installer to run? I've never worked with python before so this was an unexpected hurdle."
For your version of MCC, please refer to
https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-install-auto-requirements.html.
o "I wonder if I installed more than necessary."
For your version of MCC, Cryptography is unnecessary since it duplicates PyCrypto functionality. Next version will work with Cryptography alone.
What I would do is install Python 2.7.latest, pip and then just pip install Cryptography and pip install Paramiko.
Regarding running MySQL with different credentials, please refer to
https://dev.mysql.com/doc/refman/5.7/en/changing-mysql-user.html.
As per MCC, the tool is starting and stopping processes on remote hosts meaning your SSH user should have enough privileges to do so. On Windows, for example, this requires Administrator privileges since everything is started as a service.
Lot of it to digest I know but that's the nature of Cluster deployment.