e6 optimization for phainon and team setup

Hi guys, so basically I gotten my first ever e6s1 for Phainon and i'm wondering what's the best setup that I can work towards. I've usually get a good grasp and learn from guides but most of it is catered to e0, I kinda need your input for e6. Purpose I have in mind is optimization to have satisfying endgame (mainly AS since it's AV, dmg, weakness breaking (0 cycle MOC and max PF scores already)

For reference with Phainon Sunday Bronya Ruanmei in all with e0 (including Phainon) - Managed to 1 cycle MOC, 40k PF, 1.7k AS.

My current Phainon build (still working to improve) : 2800 atk, 84: 204 crit, 116 spd on bis set and planar.

Teammates discussion: I hear many talks about Robin, Sparkle, Sunday, RMC, Tribbie, Ruanmei and the upcoming Cerydra. Which are good for an e6 Phainon? Would RMC true dmg buff stack and be great for Phainon?

Sunday: What speed to aim for, 4 pc Sacerdos for sure but 2p Lushaka or 2p Vonwacq?

Cerydra: Similarly, what do I farm for her and stats aim?

Last slot: who to put? Build and stats.

I'm mainly asking this because my other team is probably much weaker such as having Castorice e0s1 without Tribbie and Hyacine (saved for Kevin and Fate). So I wanna make more leeway for other team xD as well as having satisfying Phainon performance. Also my first time owning maxed cons char across all gachas, hence a little bit lost, I only had e1 Jingliu and all other limited five stars are e0. I don't mind having to pull Cerydra or Huohuo etc. as long as they can complete my Phainon team. I haven't tried DU higher difficulty but presumably I won't be struggling there with an e6 Phainon, correct me if I'm wrong tho.

Thank you all for reading, appreciate any inputs Phainon enjoyers!

TLDR: What's the best optimal best team setup, build, stats, rotation for an e6 Phainon? Assuming 5 star limited e0 and 4 star limited e6.