Wheels are hot

They will be considerably warmer than your non brake axle, and they will be slightly warmer than your front brakes on your vehicle. Compare the temperature to your front vehicle brakes.

Not really, just check the fluid.

What type of break fluid do I need to put in?

Also make sure the brakes are not “set”.. Under the coupler there is a release tab that you need to push up to make sure brakes are released..

It is both brake axles, so doubtful. Though do check all the caliper bolts for tension and you can loosen the calipers and reset them lubing the slide part to see if that assists the return. Turning on a radius should help flex the rotors and free them also. Then you would have to elevate the axle with brakes to check for tension on the rotors.