The cloudiness is just an algae bloom, very common in a new tank. With a bit of luck it should clear again by itself. Any plants in the tank? These will help.
Don't worry about the temperature, it is not too much for the goldfish. Over summer if it rises too much, fill some 2 or 3 litre plastic juice containers with water and freeze them. They can then float in the top of the tank and bring the temperature down. As they melt you put them back in the freezer to refreeze.
Chillers are available but are very expensive.
By the way, welcome to the fishroom