40watt TC or 200watt TC the wattage only affects initial coil heating ramp up, more watts, faster the coils ramp up to set TC temp, after that they pulse width modulate the voltage/wattage to maintain that set temp. You'll notice that with the Hellboy there will be more airflow, so you can probably add another 20 to 50F to the TC temp setting to warm up the vape, get more flavor and vapor, the extra airflow will help keep the coils cooler as well. 4 post screw setup compared to the 3 post is a bit easier to work with, I generally secure the outer post of a coil (the negative for that coil), then secure the other leg into the center hole furthest from secured negative leg (1=coil 1 negative, 2=coil 2 positive, 3=coil 1 positive, 4=coil 2 negative) which helps center the coils in the RDA, securing the first coil, cut its leads, then secure the second coil and cut its leads, the second coil center lead can be tricky to cut so shift the first coil down to the deck, mount the second coil, cut the leads then level the coils back up off the deck and center them better. If you are wanting to cloud up the room, TC builds generally can do it, but here the difference of TC wire like Nickel Ni200 and non-TC wire like Kanthal A1 or Nichrome80 differ. With non-TC wire builds the mod won't throttle itself to maintain temperature, it continues to supply the set wattage, ie mod set for 80watts, it will fire 80watts the whole time the fire button is held, which makes for a hotter build. The Stillare is in this instance better suited for TC mode, where the Hellboy with its larger deck/chamber and larger post holes can accept hotter coil builds with Kanthal with all of the airflow it has, especially with the wider chuff drip tip/mouth piece. Going hotter up the wattage scale this way if you are say using 6mg Nic per milliliter liquid and double your wattage (40watts normally in TC going up to 80watts) you'll want to go down to a 3mg in that instance (twice as hot, vaporizing twice the liquid you normally, twice the nicotine exposure). As far as power versus tank or rda, the RDA will handle higher watts better than almost any tank on the market except a few like the TFV4, VCMT, and a few others that can equal an RDA in the cloud department, they are just shy of an RDA in flavor. Remember just because a mod can do 200watts, doesn't mean you have to press the limits all the time to get a good cloud, I can build an RDA all day long with a higher ohm build parallel coil and out cloud a lot of other "Super" cloud builds of 22guage wire someone else it using at 1/3 to 1/2 the power they are using, also have to ask would you drive a Ferrari that can do 200mph at 200mph everywhere you go.
hth explains some of it a bit.