Drosera binata varieties generally become quite large. D. binata var. dichotoma 'Giant' is known to be the largest, which has been known to reach heights from 1.5-2+ feet on average. The "T-form" generally produces leaves from 6-9 inches long. D. binata var. multifida "extrema" is commonly grown in hanging baskets, since its leaves tend to "droop" in lower light conditions. However, if given plenty of light, it can grow into a large, upright bush.
Media: very adaptable. I've had success with 1:1 peat: sand (silica) as well as 100% dead or living long-fibered sphagnum. Perlite can be added as well, as needed.
Media moisture: keep moist. Drosera binata can be grown in waterlogged soils as well.
Humidity: not much needed, but I'd recommend at least 50% for optimum growth. Try 75-85+% if you want to maximal dew production.
Pot height: does quite well in smaller 2 to 3-inch pots, but the large roots can become crowded. Use taller pots (6-10+ inches tall) to encourage the largest possible growth.
Temperature: not picky. Has grown well for me in the temp range of 40-85 degrees F. If the temperatures drop any lower than that, all varieties will usually go dormant.
Lighting -Photoperiod: Give all forms of Drosera binata as much light as possible. When not outdoors, I grow mine under T-8 lights with a 16-hour photoperiod. Leaves of all forms can turn bright red if given enough light (or if not fed for a while).