what are these holes for??

my stove is cylindical, like a potbelly would be. it's ul listed for coal and wood. now on the loading door it has a slide that opens 4 holes in the door to allow air in. my question is am i correct in assuming these should be open for wood burning since would generally burns from the top, and closed for coal since coal burns from the bottom up??? or should they remain open for coal also to create a secondary burn of gasses???? ive been burning coal with them closed without any issue but i run my damper almost closed in the flue and i don't want gasses leaking into the house from these vent holes if i open them.

Closed for coal.

One use for them with coal is to open your manual damper, then open them up to clear the stove of gases so you don't get "the explosion".

Minor Explosion In Coal Stove

Try opening them just a little after you add coal, to clear the gas above the coal as Richard S. says, or (even better) to get that gas to burn rather than go up the chimney without giving up its heat value. You will have to experiment with the right combination of under-fire draft and over-fire air to get the gas to ignite. Once the initial gas rush is over, close them.

Any idea, ball-park wise, how long it takes for the gas to dissapate/burn-off before it's OK to close your upper vent(s)??

On a coal stove, they will also act as another means of controlling the burn. Open, they will slow the air flow through the coal bed.

I shake down, open the bottom air wide open and open the two on my door about the width of a finger. Then load up while keeping a few spots open for the flames and glowing coals to ignite the gasses. I check mine after about 15 minutes to see how tall the blue flames are. If they are real tall I let it burn about another 15 minutes then close the door vents tight and choke off the bottom till I get the desired air flow. In a half an hour with the damper in the stove pipe closed way down the fire will burn right if the air from below is correct. If it isn't putting out the heat I want I open the bottom air a little more and keep an eye on it to make sure the fire perks up to the desired temperature.
I'm heating almost 2400 square feet with only my stove downstairs. 75 to 80 downstairs and 68 to 70 upstairs by natural convection. When it gets cold again, I'll build a fire upstairs to stay warm, then choke down the output a little downstairs so its comfortable but not overly hot.
Clear as Mud?