If you feel like it. SSR kami isn't necessary for completing game or doing events, they help out but aren't necessity. Especially when they intruduce event quests when you will have to beat ulimate difficulty with only R team. And the chances are that if you play long enough you will get some SSR kamihimes.
From news section right under game:
As for her dropping from quest... Isn't it impossible? I never saw any of precious SR eidolons dropping from quests (I will admit that I didn't try to get them drop), so I don't know. Even if she does drop isn't it supposed to be very rare?We have received some inquiries about the material exchange shop.
When you try to exchange "Melusine" with the material, an error will occur.
Now we are investigating.
We will make another announcement when we finish it.
We thank you for your kind understanding and continued support.
Sincerely,
Dev Team
About upgrade quests... I am pretty sure I saw them last sunday, at least I think so.