Ah, so you've got the best upgrade, Durango brakes, very nice.

About the brake fluid, i change the fluid every 2 years, when refresh the fluid regularly there shouldn't be much or no debris at all in the calipers.
When you take them apart and blow the pistons out of the calipers you might see a little brown fluid, but it's because of the dismanteling, when they pop out the fluid made contact with the unused and a little rusty spot on the calipers.
So with regular fluid changes, you shouldn't have to take them apart, only when they are stuck, or leaking.

For regular brake maintenance, i clean them every year, the outside like brake pads and slide pins on the calipers and the rotors it self,
Clean the rotors by removing the rust at the edge and remove the edge with a grinder ( not necessary ) if present.
They should be cleaned every year and put new grease on the slide pins and contact sides of the pads ( back and slide ).
This way i always know how my brakes are doing.

 

I am curious to see how much comes out of the caliper bore with a brake clean flush. I did this multiple times on the ones installed yesterday and was surprised at how much came out, even the one that was a re-man one had gunk in it.

 

When compressing the piston, I always open the bleeder nipples so the fluid right behind the piston gets pushed out instead of back up into the lines. That's the dirtiest fluid which has undergone the highest temps. I flush every three years or so.... tight fitting clear hose on nipple goes down into a water bottle where the tip is submerged in brake fluid (prevents air suction), then pump away. I always check the slide pins and steel wool any imperfectioons. Also change any boots that seems to collapse easily and tear/develop cracks. These are rear boots I did a few years back... .

Brakes work great as attested by my wife after she slapped me in the head for not paying attention on the highway. Was going about 60 and not paying attention to stopped traffic. They locked up pretty nice with lots of burnt rubber. Only a little underwear leakage.

 

I plan to do new pads & rotors in the next few months, the goal was always to get it working, then replace with new when needed.

What is going to be interesting is to see how much junk comes out of the Rams front calipers. They have been in service since mid 2017 and have had the flush done on every 50k click of the odo. The rears, have no idea how long those have been in there, would have to dig thru paperwork to find the receipt (all in a box). If the fronts release a lot of debris then I may put servicing them (bench flush) on the 100k service list. I will post up findings here when I get there.

est odometer = 183k