Licensing issue with Red Hat Subscriptions

I would like to know how the terms of subscriptions work on any developer subscriptions(including paid and no-cost) for the following cases:

1. Hardware development.
2. General computer science research and experiments when the report is the main aim rather than the actual software code involved.
3. A developer using the same machine as personal computer for his/her own private non-commercial things. (using other CentOS loses the devtools channel for development purposes and self-supported production does not provide devtools, or possibly can't mix subscription variants to stay within the support terms).
4. Merely using RHEL to run software development tools but the target of the code is not a PC/server which has nothing to do with RHEL.