u/A_Pinecone_Of_Dipper

Soooo, i tried to build an Overload Razor team, and i have some confusion:

1.Who would be better for him, Nicole or Fischl?

2.I am currently going with a Razor/Nicole/Durin/Chevruse team, and:
-Razor is lvl80, 2.5k atk, 57/140 cv and 120%ER, I’m using Wolf’s Gravestone and 4pc Rising wings,c0, talents at 6/3/7
-Durin is lv90, C0R1, 2k atk, 62/208 cv and 142%ER with 4pc Rising winds and talents at 1/5/8
-Nicole is lvl 90, C0R1, 2.7k atk, 216%ER on lvl 80 Fav, 4pc Celestial Gift and talents at 1/8/7
-Chevruse is at lvl 70, 33k hp, Fontaine craftable, 4pc Songs of Days Past, C3, talents at 1/7/1

Is there anything that i can do to improve this?

Thanks in advance.

So, i am trying to build ifa as a main dps (bcs i have the chance, and why not).
Currently he's on the windslith(lvl70), lvl 60(i'm working on his lvl, dont worry) and 4-piece obsidian
His crit value is 47/218 and 1500 atk(with pyro resonance)
His talents are at 4/4/4
How can i improve him? And should i use Mappa Mare?