I am not sure what fuse is for the Seats but look it up in your manual should say.
Check for power at the fuse point.
Then see where the wiring goes from the back of the fuse panel.
If the Panel is fused properly then run the wires but if not or you can’t determine the best hook up do the battery thing.
(Note: If the power side is there but not the load side of the fuse, you can get connectors from another Panel to work with your and there you have it).
For the battery setup:
Run a fused (15A or 20A) 12 gauge wire from the battery to one seat then to the other.
Grounds can be done as you stated but while you are doing it run the ground to the battery too.
4x4, 5sp, Std Cab, Stepside, E4 Red
4” Lift - Coil-Overs, 6” SkyJacker Leafs - No Blocks (Mistake)
31 Spline FX4 Rear Axle, 4.56s and OX Locker, Hurst Shifter w/Optional Stick and "Made by Grev" alignment adapter