Lived in the eastern suburbs of Sydney for over 40 years now. Never had a problem with the temperatures being too hot or too cold. Only need heating for 6-8 weeks a year, only need cooling intermittently. Can manage quite well without any A/C as long as fans available for the few very hot days experienced each summer.
Never had fly screens on any property we've lived in here. Mosquitos not a problem, flies not a problem, spiders not a problem. Cockroaches are the biggest issue; they're endemic in the beachside suburbs and impossible to get rid of entirely though you do get used to them.