Hi Finnegan,
First of all, I would take a deep breath and relax. Constipated fish will not eat like pigs. Endler's are quick and aggressive feeders, so feeding other fish with a tank full of Endler's or even guppies can be a problem. For instance, I have noticed that Daisy's rice fish fry and Indian rice fish fry do not do well with guppy fry. This is because the guppie fry out compete the rice fish fry. I haven't tried raising anything with my Endlers. They never stop eating.
It may be that the Endler's will not be good tank mates for your CPDs. Although I think they should be fine. I would start by feeding enough to allow the CPDs to eat what they need and not worry about the Endler's. You may eventually have to bring the Endlers back if they are too competitive. You may have to bring some of them back when they start having tons of babies anyway. It may just be the case that you need to try a different food. Repashy foods sink and offer the fish a bit of grazing time. They also offer ottos a good food source. By the way Ottos are not an easy fish to keep fed. I would guess that many more ottos die within the first few weeks than ever make it past the first two months. I think Repashy is definitely the way to go, once you get them. When you get your betta, I highly recommend Ocean Nutrition Betta Pellets. They will be a bit large for your Endler's and everything seems to like them. I use them for many of my killifish and killifish are notoriously finicky about dry food.
You didn't tell us how big your tank is or how many CPDs and Endler's you have. That info is always helpful.
Good luck with your adventure,
Chris