My angel became extremely aggressive at about 2 years, after living peacefully with my goldfish the whole time. It was a mistake made before doing the proper research, and when they seemed to get along i thought I was in the clear. Then i found myself having to find a new home for a gorgeous white and gold angelfish that I was rather attached to, after he started chasing the goldfish around tearing scales off of them.
Angels often seem to be peaceful when they are young, and then once they mature they show their cichlid aggressiveness.
As to temp, I keep my goldfish at about 72, have for three years, and they are thriving. Goldfish survive at a wide variety of temperatures, and although excessively high temps, up into the low 80s, can severely stress fish, mine show absolutely no signs of stress until the temps move up past 79 or 80.