Wow man. Those pictures are huge. And that is some good looking welding.
Anyway, first thing is that you should start with plain charcoal briquettes instead of the lump charcoal to help with the temp control. Once you get the hang of it, you can start mixing in some lump more and more until you're happy with it.
Second thing, in your fire basket with ash pan, does it have any hole in the bottom? It shouldn't because if you did, the coals in the middle (as your picture of your fire basket shows) will burn up quicker, leaving the other coals hanging around. But if the ash pan is sold, it will distribute that incoming air to indeed let your coals burn all around.
But what I can't tell in the picture, is if the fire basket has legs to stand in the ash pan. It should not be just resting on it without legs because then the air will not circulate properly into the coals.
Finally, you don't need a damper on the exhaust except to close it up when you're done. during cooking always leave the exhaust fully opened and control temp only by the intake.