Hi All - looking for some advice on rescuing some 100 y/o 2" oak floors (and saving my wallet, as new floors from a pro are not an option).

Many places of the floor are splintering, exposing the tongue and providing splinters in our feet. The house is old, and I like that, plus I have a couple large dogs, so the fix doesn't need to look perfect but the floors still need do need to look good. I'm thinking to replace damaged boards and refinish with waterlox but had a few questions:

1. Given the current state of things, is there an option for staining a darker color? I'm afraid to sand further, so thinking safest option is a screen and recoat but am not sure if stain/waterlox could be applied over a screened floor.

2. 2" flooring isn't as easy to source as 2 1/4", how good or bad of an idea is it to get some 4" or 5" planks and rip them to 2"?

3. Based on the photos below, think I'm better off doing all new floors myself rather than replacing many individual sections?

Any other thoughts or words of encouragement?

You may have old growth flooring which has a different look than flooring that is produced for sale, now. While it is great to be able to have an old floor, it takes more work with a thin floor because stresses can break parts of it.
This floor would only be good to look at, instead of living on it, since you see it is splintering. Any time spent trying to put any finish on top of what is there would not be a good investment. This floor may have only started out three-eighths of an inch thick, so two sandings may be all that it would take before starting to splinter in traffic areas. It's futile to replace only some areas and think you can sand the whole floor to blend.
Start saving for a new two and a quarter inch strip floor. And be careful in stocking feet because of the splintering .