That rub looks tasty. I had been struggling with my fire at first too. I had my coals sitting on a grating so that the ashes would fall throught to the box underneath. I could get some great heat but it would only last :30 to :45 tops. As a result, I'd get some hellatious temperature swings inside my smoker. One day, I had some chicken quarters and fajitas and decided to try putting the coals directly in the ash drawer. I've been doing that ever since. I get a consistent temperature for about 1:45 before it starts to slowly decrease. I've also seen a dramatic improvement with the smoke rings (weird..).
As far as the smoke goes, I get a ton of smoke at first (or when I add more briquettes). Then it reduces to a thinner puffy cloud like output. Then there comes a point when the smoker emits virtually NO smoke. I've learned that the quantity of smoke within the cooking chamber isn't that important - the temperature is what seems to help the smoke penetrate the meat. I could be wrong but that's been my observation.
Ventilation is also very important. I don't have a way to regulate the output but I keep the input ALMOST to the point suffocation. That way, I get a long, even burn.
I hope you're able to solve your heat problem. Happy Smoking