The potential problems with removal of runner are dependent upon how the runner was installed. Some dearies actually tack the runner to the steps, tread and riser. Ouch, because removal leaves those holes to be filled and stained to match (very difficult to conceal). An alternative method is to use carpet bars which come in wood or metal, in an assortment of finishes. This is slightly more expensive but imo, also *looks* more luxurious. The carpet is barred at the back of the tread where it meets the riser; best practice has the runner tacked beneath each tread rather than slanted from top-front to the back of the next lower riser. Note that under-tread tacking also uses the most running feet of carpet, so the most finished appearance is going to cost. There are several other methods, so discuss intent with the installer before s/he does the work. One thing for sure, is to not use any sort of sticky-back tape: it either doesn't hold well, or holds too well and removel is labor-intensive. Because of the carpet pile height, if possible choose treads that are slightly deeper than usual so as to maintain fully safe depth.

I don't think the issue of matching is too difficult, those look like pretty standard oak floors. If you install and only finish the new floors, the finish won't be exactly the same, but I bet they can come close. If you can afford to re- finish all of the floors they will probably be able to get them to look uniform. We had a bid to put new wood in and refinish all other wood in the house to match that was about $5000. Your space to install new looks bigger than ours, but we had a lot to refinish, so I don't know if that gives you a ballpark. You could tear out the tile and do a laminate in both rooms with a threshold at the hallway. If you don't try to match, but rather, coordinate that might work. A new tile in both would work, but might be cold on the feet in the winter in your living room. The choices are endless if you decide to start from scratch, its just a matter of taste and budget.

Most economical = carpet. After that, a solid finish (wood, cork, vinyl, tile, stone, etc) will require all the extras. Painted stairs will work...with plenty of elbow grease and with the FULL UNDERSTANDING the paint will wear/chip/"patina" inside of a few years. There are ways to lay a runner on the stairs and then trim out the edges of the tread/riser with wood-looking stuff. This will cut the cost in half of what I mention above. The other option is to place the runner and PAINT out the edges....creating a faux-painted-wood look which could be very handsome yet extremely practical. Notice how carpet keeps on coming up again and again? Yah. There's a reason for that. Those are builder grades stairs made for carpet.

heritage, I know you didn't . I was just mentioning the unsafe part regarding kids in case the op didn't know. Stairs and balusters are all unsafe when it comes to kids. doesn't matter what they're made of. kids will climb on anything. that's why I mentioned the teaching part. it was nothing against your comment.