Showing is easy. Really easy. You fill out your entry paperwork and send it in. About two weeks out from the show you start to cage train your birds and get them used to handling. Then you get the get the birds prepped, drive to the show, find your cages, do last minute prep on the birds, put the birds in the cages. Done. The judges handle it from there. The tricky part is breeding birds good enough to win, lol. The actual showing part is easy.
I'm NPIP. You may or may not be able to become NPIP in your state with only ducks. My state doesn't require pullorum testing for waterfowl, because they just don't get, and most shows won't require that they be pullorum tested to enter either, unlike chickens.
So, in my state, they don't test your waterfowl when they do NPIP testing. If your other birds test clean, then your waterfowl are considered clean too. If I just had waterfowl, I'm pretty sure they wouldn't test or certify my flock, because they just don't test waterfowl.
The paperwork is minimal. You fill out a form when you sell to someone, and if you ask, you can get access to the online database and do it all on online. And, of course, you can only buy from people who are NPIP certified, so you need to get paperwork from them when you buy birds to show that they are NPIP certified. But that's it as far as paperwork goes.