Even without knowing the kind of wood or condition, I can't imagine replacing wood flooring in an 1890 home. In my opinion, the value is in the original material. If the floor is in good condition, it may not need sanding at all; a screening and recoat might be all that's necessary and the patina would be retained. There are many threads on this topic, try searching the Old House forum. I live in a converted schoolhouse built in 1890. The fir floors had been covered with layers of linoleum, glue, paint ... they were a mess.. but looked awesome after refinishing. That was years ago and I'm planning to have them screened soon (aka buff and recoat.) What kind of wood is it? Do you have photos?

I hope everything works out to your satisfaction. I cringe when I see that transition. I also had flooring installed to match existing hardwood, both of which come off a higher kitchen floor. When they installed my transition thresholds, they were 1 1/4 high with no slope! When I said that was unacceptable, he said that looked the best with the "massive height difference" and ugly tile edge. No way can that be code. Meanwhile there is a perfectly acceptable reducing threshold right across from his installed by somebody else. Thank goodness you have someone who will work with you for such a big job. I just got sick of talking about it. I was able to find a 3/4 reducer, cut it to fit with a small lip over the tile. If the edge is not perfect I'll run some grout. The poly is drying on it to match floor. Installing them tomorrow.

The stairs should be considered part of the 'public' areas. That means they should match/compliment the downstairs area (the place with the entrance, the living/dining space, etc) where guests come in and move around. Traditionally 'upstairs' would mean private space such as bedrooms. The upstairs areas are welcome to have different flooring from downstairs. That's not a problem. You are welcome to work with treads that are 2-3 steps darker than your downstairs flooring and then paint the risers. This is a very handsome look that will show off both the stairs and the down stairs flooring. If you are lucky, you will be able to pick a stain/finish that is complimentary to BOTH floor colours. Of course, a stairway that has been designed for carpet has a different set up than one designed for rigid flooring. You will need to be careful with how the finishing carpenter finishes the stairs.

Usually the nosing is measured out onto the subfloor and the laminate planks are cut and floated UP TO the line. You've gone about it the hard way = lay flooring AND THEN cut back. It can be done it's just trickier to do it this way. A floor cutter would do really well with this one.