Definately do not feed beefheart, as omnivore/herbivore digestive tracts aren't built to handle such heavy protein.
As for the rest, honestly I would do a mix of a high quality cichlid pellet (I used New Life Spectrum when I had cichlids, but the one you were using is good too) as the base of the diet, then supplement with bloodworms and/or mysis shrimp maybe a couple times a week, as well as some real vegetables every now and then (sometimes if fish are used to pellets and meaty foods they don't go for the raw veggies, but some really seem to like it).
To feed a leafy vegetable, you can either buy one of those algae clips they sell for saltwater aquariums and just stick that in the tank and clip the spinach or algae (or whatever) into it, or you can just rubber band it to a rock or whatever. The same goes for slices of zucchini... just rubber band a piece of the vegetable to a rock or something in the tank. I have never heard of anyone ever feeding fruit to their fish, so I would hesitate to give advice on that matter, but I would imagine there are probably some fruits that might be ok. I wouldn't do a slice of orange though, just because of the acidity and it possibly affecting the water chemistry. I do know that cucumber, zucchini, peas, romaine lettuce, spinach and carrots are all good. It's best to soften the harder veggies a bit before you feed the fish, either by freezing them and then allowing them to thaw, or by steaming.
I know that severums usually like fresh veggies. The rest of your cichlids seem for the most part to be more omnivorous, so I can't say whether they will really like them or not, but it's not a bad idea to give it a try. Just remember to take out anything they don't eat so it doesn't decay into the water.