Tropical temperature range is considered to be 72-84º F/22-29º C Below this range for room temperature (coldwater) aquariums.
Time light is left on would largely depend on the plants, if any, you’re keeping with the fish. Generally, no more than 8 hours.

It depends on what fish u have some like cooler some like hotter water.My grandad has his tank at 32 degrees no matter what fish he has.My tank is at 26.there some good wed sites go to askjeeves.com.And look up keeping fish

There are as many correct answers as there are species of fishes. Each species will have an ideal range of temperatures. You should research every specie you keep and do it before purchasing.
If your water change schedule keeps the nutrient levels low enough that you can avoid heavy algae growth,the photoperiod in the tropics is always 12 hours of light and 12 hours of darkness. The twilight periods are almost non-existent, it goes from bright sunset to dark in a very short period of time.

I try to keep my tank at 78F. It depends on the fish though. Some like warmer and some cooler.

Between 28-38 degrees. You should leave the light on for 8-12 hours a day.

most tropical fish live in a range of 72-84, I keep my tanks at 78-80, lights really only need to be on for 3 hours a day, I keep mine on for 5 1/2, many people keep them on 8 hours or more but this adds to brown algae buildup

The water temperature depends upon the fish you have in your aquarium. For “typical” freshwater fish, the temp in my aquariums is between 70 and 78 F. There are others that require higher or lower temps, for instance blind cave fish can take 63-75 F, and Bettas as high as 70-85 F.

Saltwater aquarium fish typically come from the tropics, so 75-80 F is best.

As for lighting, I keep my lights on about 8-12 hours per day. When I wake up, they come on, when I finish feeding them at night, the lights are turned off. Fish require some light, but so does algae. The more light you give, the more algae growth you’ll have, so there’s a bit of a balance with lighting.

Fresh water or Marine (salt)
If freshwater, 74 degrees, I believe. As for the light; provided you don’t have the tank in direct sunlight, which will not only heat the water, but also bring out algae, leaving the light on half the day will be fine. There’s no set rule to how long the light should stay on as it all depends upon what you have in the tank for vegetation, fish and other ornaments.

room temp.
just let the water sit out over night and it will be good
all the chlorine will have evaporated.

i have one and i find that about 35 to 40 degrees is perfect. I know it sounds too high but it’s true.