red's are more nippy. yellows tolerate handling a little better. they are all individual. if starting with young, it doesn't really matter.
20 gallon longs for hatchlings, 40 breeders for sub adult and 4'x2'x2' for adults.
bricks and slate do well, or make a stack. they like to wedge themselves in crevices. deep substrate works, i use topsoil for adults, but my young blackhead monitor is on a mix i found near my house. it's a red clay sand mix. hardens up to support a burrow. i don't think it could be duplicated easy or is sold anywhere.
i use 45-50 watt halogen flood lights on mine. no uv is needed if insects are supplemented and whole prey is offered (prey with vertebrate). a fuzzy every now and then doesn't hurt. get the basking spot up to 130F with a temp gun. an elevated basking area (such as stacks) help reduce the need of so much wattage and burning up humidity. they don't want to be extremely hot all the time. so let the opposite cooler side stay around 80. with deep enough substrate, they'll also burrow to escape the heat. this doesn't mean it's too hot, it means they are doing what they instinctively do.