The culprit is most likely the Yoyo Loach. It mentions in our profile that this loach should not be combined with sedate long-finned fish--such as angelfish, as it may fin nip.
Also, loaches should be in small groups of each species; being on its own will often increase a fish's natural aggression. Though regardless of numbers, the nipping is still going to occur as I noted. The rapid demise of the angelfish would at first suggest possible disease brought in with the newer loaches, but not necessarily; your observation of torn fins confirms in my mind that the loach/loaches were likely responsible. The Yoyo is probably the culprit; the Clown Loach should also not be kept with angelfish because of the loach's active nature, though I can't rule out nipping here too.
The harassment/nipping likely stressed the angelfish and they died. [You may find my article on stress useful, here: http://www.tropicalfishkeeping.com/f...um-fish-98852/
]. The subsequent eye and body issues would naturally occur with any dead fish if loaches or the pleco find the corpse, and they would.
If you decide on angelfish, I would return all loaches. Better substrate fish would by any of the cory catfish. And i would also lower the temperature, since 80F is a bit high for angelfish that are captive bred which I am assuming these are, since they are not the original species but colour/variant morphs. A max of 77-78F is sufficient. It is always best not maintain any fish at the high end of its temperature range, since the warmer the temp, the harder the fish must work just to "live" normally.