Completely lost about Kokomi’s scaling

So as many of you I really her aesthetic and I’m also in need of a water character to go along with my diluc/ayaka/xiangling.

I decided to pull for Kokomi but I’m really unsure about how she works since I keep seeing différents opinion and stuff on her. I want my kokomi to do nice damage and I absolutely don’t care about healing since I already have Bennett and Jean C1

1. Healing bonus, why does healing bonus hat would be the best damage dealing option for her? Where does she scale from it?

2. Set, I was thinking of 2 pc NO and 2 pc HoD but I’ve never seen anyone talking about NO. Is the 20% on burst less good than a healing bonus or a 20%hp from ToM?

3. Atk% and Hp%, are we sure that hp% scale better than atk during her ult? I can imagine both working together with maybe a little more for HP% but then ATK% would still up her elemental skill and autoatk

4. I saw people talking about her C1, what does it do?

5. Is the Hp% prototype weapon a good choice on her? I like the energy particles that it creates but don’t know if that would be consistent

About her role in my team I really want her to be used for the whole length or her ult doing big vaporisation damage with xiangling ult for example