1. Don't waste your money burning oil in this unit. Testing will show you that, as an oil burner, you ought to scrap it. It's just not worth it; there are far better units. A new unit will pay for itself in less than 1 year given the 30% better efficiency you'll enjoy in a 2000sq ft home.
2. Yes, it burns wood. Effectively. And I did it right here in mid-winter in CNY. But here's the thing: you better have a lot of wood and you should either work-from-home or have a job that has you (or someone else) home every 6-8 hours because that's how often you'll need to load it. Sure, you can load it up to the rafters before bed and snuggle in for long overnight slumber and still have some burning embers in the morning. But the temperature will have fallen pretty significantly and the Samson thermostatically-controlled damper will be wide open. Wide open enough that it will be actively drafting tons of air through the unit and further cooling it. So, in the am you can wake up and easily get it going again. But don't think that you can then grab your coffee and climb in the truck and go to work. Nope. Not a good idea. The fire will restart, for sure. But because it is a high mass boiler with 1000# of steel and 320# of water, that fire is going to be BLAZING for quite some time before that damper begins to close around the thermostatic setting. I have seriously over-fired this unit to the point that the chimney pipe changed color and became brittle, ruined. If the boiler is near the target temp when you reload it, sure, you can go right on your way. But not if it is cooled down significantly. So, if you choose to use wood, plan on being married to it.
3. Coal is an entirely different story: it burned either stove of nut exceptionally well. With around 75-100# in it, it would easily burn all day without the above problems. Yes, you gotta shovel it in and shake it down 1-2 times a day, and, yes, it will waste more coal than any modern stoker. But not enough to meaningfully justify the additional cost of new stoker.
Here's a few more tidbits:
a) Use the unit only when it is cold, regardless of whether you use wood or coal. This bad boy will easily put out 140K BTU. But to keep even a small fire burning through a deep bed, you need draft. And you only get draft from chimney height, diameter, and temperature differential. You usually don't adjust the first 2 but weather changes the differential. And that little fire can get really smoldery and smokey on those warmer fall and spring days. It looks like an outdoor wood boiler. And you'll definitely need a "dump zone" to dump excess heat, especially on those warm days. The windows will be open and the inside of the house will over 80F. It will be perfection, however, during the cold months.
b) The Samson thermostatic draft controller will keep that high mass boiler pegged pretty close to target. Mine was just that good. But, you MUST make adjustments if you want to switch between wood and coal. I advise that you optimize for one or the other; don't try to switch back and forth.
c) Similarly: if you go with coal, use a baro draft regulator. If wood, I would avoid it. My concern is that creosote in this boiler is a BIG problem. Huge. All those hot volatile creosote gases directly condensing on the unlined steel smoke paths (which are water cooled 1/4" away) really does happen. I never had a chimney fire, but if I had, I'm sure the baro damper would have swung wide open and feed it like crazy.
If you have more questions feel free to ask!
Best of luck!