Let me see if I can help at all. I'm not an expert but I've learned quite a bit along the way so I'll share what I do and what works for me, other people have different opinions and experiences than I do so they may do things differently.
First off, heat comes from fire. Fire needs a fuel source like gas or charcoal and oxygen. If you increase the amount of oxygen you increase the heat, if you decrease the amount of oxygen........
Just being a smart ass there
I like to control temps with my bottom vents only. I want as much exhaust coming out of the kettle so I always leave my top vent wide open unless no other tricks are bringing my smoking temp down from a runaway. I believe closing off the top vent while smoking/barbecuing can put "bad smoke flavor" and soot on the food and no one wants to taste a camp fire in their ribs or pulled pork. Smoke flavor should be an essence in my opinion, not a flavor that overpowers the rub and the protein. If I want to taste smoke I'll just stick my head over a camp fire.
I've had the most success with the snake method when smoking. I usually light 10-14 briquettes at the head and let them get good and ashed over while preparing the meat with the rub and getting my drip pan with water ready. Here is the biggest tip in my opinion, don't shoot for a target temperature. Shoot for a temperature range. Kettles aren't ovens and you will have some fluctuation during a cook, if you try to maintain 230 for 12 hours straight you will be tired and pissed off. I like my range to be 230-260 most of the time, if I'm in that range I'm happy.
Smoke flavor. I love peach wood and pecan wood better than the rest. I only use a couple nice sized chunks and I place them towards the head of the snake. Why at the head you ask? Meat takes on smoke when it is cold and or wet. Smoke bounces off of warm dry surfaces. Remember, I don't like a lot of smoke flavor, so much that you don't taste the rub or meat. If you want more smoke on your meat you will have to keep spraying it lightly throughout the cook with water. Only use chunks of wood and keep them dry and seasoned, don't soak the chunks and avoid wood chips if possible. Smoke color out of the top vent should be a pale blue color. White and gray mean soot and the fire is starving for oxygen.
Grilling is easier. Light 1/3 chimney, toss the lit coals to a pile and use a 2 zone fire. Grill over the coals and move food around as it cooks to avoid over cooking it. Sounds like you have grilling under control. If you are going to try smoking I suggest you start out with a small pork shoulder roast. It's pretty hard to mess up a shoulder roast and if you get it right it's a very nice meal. I suggest a roast cut because it shouldn't take more than 3-4 hours and you can experiment to learn what works for you. Then you could move on to ribs and larger cuts of pork and beef.
Takeaways:
Aim for a target temp range, not a single temp.
Aim for blue smoke.
Snake methods are pretty bullet proof and you don't need to spend money on smoking gadgets and accessories.
HAVE FUN COOKING! If it isn't fun, just use the oven.