The trailer should generally stop itself and the truck stop itself also, so you can set the brakes to where the truck feels like it normally does when slowing down, maybe err slightly to the side of the truck doing a hair more braking than normal; doing a little braking for the trailer.
You do not want it to skid ever, and pavement settings might cause the trailer to skid on gravel roads. Not a big deal, just adjust if you are on gravel for a while.
Trailer brakes will go out of adjustment, so need to be adjusted, otherwise one wheels will do more breaking, and might skid, while another wheel might be contributing no braking.
tandem axles require a lot more attention than single axles.
Your bouncing could also be from sloppy receiver connections. The insert can wobble around, and even your trailer tongue can be loose on the ball. Get a spare ball and lock it in the trailer tongue and adjust the nut underneath until it is snug, but in no way binging.
There are U-bolt clamps and other solutions to take the play out of the receiver square insert also. This makes a big difference.
There should be tension on the weight distribution hitch springs (long arms), and the chains should have tension when on flat ground. If too loose then you can get bouncy issues the same as with no WD hitch.
Too much weight behind the axles can also unweight the tongue and make more bounce.
My truck drives smoother than not towing with the WD hitch on and the slop eliminated from the hitch.