For voip there is a voice threshold setting, you’ll have to google it as I can’t remember off the top of my head.
For the low gravity mode, set the movement mode to LowGrav with SetReplicatedMovementMode (with the normal nodes you have to define custom and then the custom number, that node packages it neatly).
It retains momentum without gravity influencing, you can boost with Add Impulse / Add Force or you can feed in CustomMovement commands like with the climbing movement mode. You can also set the PostClimbingMovementMode to LowGrav to have it seamlessly transition out from it and climbing. If you need to use it in multiplayer with rollback working correctly then if you are using addforce/impulse, you’ll want to use a Custom_MoveAction that applies it, that way it replicates correctly since those nodes do not normally replicate on engine characters.
https://i.imgur.com/YA585aB.png
And yeah, you don’t want to simulate the root component of a character when the character movement component is active.