Awakening and retiring: help me get it right

I’m trying to get the proper process around awakening heroes and then retiring the “right’ copies that I don’t need. Here’s what I understand:

1. I should only awaken my DD heroes
2. If I get <= C+ I should retire those for starry gems
3. Purification is a waste of awakened sheep copies that could be retired
4. Anything above A- is great, but not necessary, as A- is the minimum for the extra stat boost and ability tied to it

I guess my questions are: Is the above accurate or would you modify anything? And, if all my heroes already B-rated, should I also retire any B copies for starry gems or is it worth saving those for elsewhere?

Thanks in advance.