Any species of fish sparking your interest? Tangs, angels, puffers, triggers, groupers, eels, wrasses, other species? Planning out a tentative stocking list is important to get an idea for filtration. If you plan on keeping fish that consume large amounts of food like puffers, triggers, groupers, eels then filtration sizing and type will be impacted versus a tank with just tangs, butterflies, angels, or even a tank with all small species like damesls, chromis, psudochromis.
Yes I would heat the room if possible. Of course have heaters for back up but budget wise I’d go with a heated room.
Radiant heating system that utilizes a heat exchanger. I use a pex coil with redundant temp controllers to maintain my systems heat. Controlling the room temp is an option but it would need to have both heating and cooling capacity and would take some time to raise the water temp to where it needs to be compared to just heating the water directly which will raise the air temp in the room that holds the tank. Humidity control will also need to be considered based on the space housing the tank and your climate.
