So, your putting up a chimney, and your going to power vent??? That doesn't seem like a good idea at all. If your going to put up the chimney, forget the maintenance heavy, failure prone power/direct vent.
Now to the chimney. The chimney is a good idea. Masonry is best but, you do what you got to do. Do not get the triple wall, it is not insulated. This means you will not be able to maintain a draft on your stove. This will lead to outfires and fumes coming out of your hopper into the house instead of up the chimney.
A power vent is the easiest way to vent. You don't need a chimney, just a hole in the wall. The problem with all power/direct vents is, on a coal stoker they have to run 42/7 and are in a corrosive environment. This leads to chronic problems/failures.