I'm in no way a stove expert, never built one, only used a couple Kifaru made ones. That said I have used mine a lot above tree line and fuel makes a difference.
First off, on these light stoves, with all the air leaks, IMHO a stack dampener is useless. You can't really load it up without it running away and if you dampen the stack smoke will backup and leak from all the air sources.
I believe some of your issue may be stack length too short, stack length seems to make more draft.
I try to keep a steady fire, slowly feeding it as needed. Can't really stuff it full without it getting too hot.
I try to always have some sort of starter,, compressed fire logs like dura-logs cut into small pieces work best to get it going and then add whatever I can find to burn. I bring fire paste or lint soaked in vaseline, I have even used charcoal. All this stuff burns and does not fly out so if I have weight I bring in all I can.
I line the bottom with gravel to hold heat and like you mentioned use the top to warm and dry the next load to burn.
You have to remember that almost all the fuel except spruce or birch is garbage and does not burn well at all.
A couple tools makes a huge difference, for one when breaking up your wood using a large rock to lean your wood against and another to lift over your head and break the wood near the brace rock is very effective and much easier than sawing or using your knee.
A straw, tube, pipe etc.. to use to concentrate fresh air into the stove to stoke it. Using the tube you can slowly blow air in and get it blazing again. I use my small micro fan to do the same. This little fan is for blowing up air mats but is awesome for stoking the fire.
Some river here have natural coal and that stuff works great if you ever find any.
