The only person who could even begin to tell you that would be either a fireplace contractor, a mason, or an architect. If it was built originally as a fireplace, that's one thing. You'd have the structure you needed. If not, if it was built as a chimney specifically for use with a stove, you'd have to build a firebox, a proper hearth, etc., and that could get VERY expensive. In this day and age your best bet isn't to get rid of the stove in favor of a fireplace. If you want the ambiance of a fireplace, get a stove with a large viewing area, one that can have the doors open (with a screen across the opening) that will serve not only as a fireplace for ambiance, but also an efficient heating stove when you don't want the fireplace function.

When we move we will be taking our stove with us but because I dont want to disturb our roof, ( we have a rubber membrane roof), we are leaving the diffuser at the ceiling and the triple wall/ vent cap on the roof in place. Whoever buys the place will have the option of installing another stove or removing the upper mechanicals. If you want yours removed, I would seek out a reputable handyman that has experience in siding repair, carpentry, roof repair as well as painting. Make sure you check them out pertaining to the experience by getting references and referalls from friends, family, co- workers, etc who have had similar projects done and they are satisfied with that persons work. Make sure they are insured and legal!

"Is it really that big a deal to replace shingles"? No, but it's more difficult if your shingles have been down for a good time and are sealed well. It's best to remove the shingles around the area early in the a.m. when it's cool and the shingles haven't had a chance to warm up. You have to be a little more careful as they are a bit more brittle when cold, but the seal tabs loosen easier when cold. A slightly curved flat bar with a nail pulling slot at the end works well to get nails or staples out from under the shingles that aren't being removed, but it's all about going slow and careful and making sure all fasteners that need to be removed are so that any left dont protrude through the existing shingles after the project is done. There are specialty tools to remove fasteners as well as nailing back under the existing shingles, but a flat bar and careful hammering gets it done as well. The shingles would be removed according to how they were layed out around the flume pipe hole removing full shingles. Cut out and replace the sheathing, lay down new underlayment,(ice and water sheild if close to the overhang and necessary in your area), re-waeve in the new shingles. Dont expect the new shingles to match up perfectly cosmetic wise. Often times even with the same manufacturer and color, they are off because of different lot numbers. Also make sure you get the same dimension shingle size wise as some are metric, while others are standard. They can differ width and length.

That wood stove is a beauty, it adds some nostalgia to the room, I wouldn't move that, try to incorporate with the new decor.