I have a few questions about hos ryoshu

What is the minimum amount of hos units do I need to have for her to become way stronger

What are the conditions for the music thingy

Do I have to kill the hos units every floor(in md) or is there a way for them to stay dead or is it unnecessary

I heard she had special ego gifts? How do I get those

What's the difference between s3 echoshear and string connection, what conditions are there to trigger each one