I'm using a Dwyer 460.
Draft fluctuates rapidly between 4 & 5-1/2, haven't had any problems. You may want to borrow one somehow to check the accuracy of yours.
As long as it's not burning into the hopper you should be OK.
Keep an eye on it on a windy day, not sure of your venting system.
I don't have a thermostat, can't be of any help.
When you shut it down for cleaning look inside, to the far left under the exhaust fan. You'll see the 'flap' that you're adjusting. If it's wide open it should be minimum draft.
I also have a basement setup.
I have a register hole about 10 feet from the unit. I ran 6" ductwork close to the heater, suspended by wire.
I took metal flashing, shaped it like a cone, attached it to the 6" duct close to the stove to get as much of the heat possible going upstairs.
Cold air return on the far side of the house.