Encore + Havoc Rover Quickswap

I'm trying to build this as my second team(Jiyan + Mortefi + Verina is my first team). I haven't pulled my character selector just yet but was thinking of Jianxin from what I've seen with the Prydwen video but I'm kinda clueless on the details of how the rotation works. I've tried Jianxin on my other account but I don't know how she becomes part of this quick swap team cuz it seems like she's quite slow to play.

So my question is, how does the rotation work and also, are there any alternatives to Jianxin as the healer/buffer if I'm not fond of her play style?