Pine floors need a soft varnish, hard varnish will chip when it's on a softer surface. Personally I like natural pine. You could give it a pale grey wash or maybe a chocolate brown, to prevent it from looking too yellow once it starts to darken again (uv light). I'd stay away from the honey-caramel-tones, because it will go there on it's own.

Hi- I see no one has answered to you as yet. I would do a search on here within the photo section for dark wood floors and whatever wall colour you may have in mind and see what comes up. Play around with different wording and room selection, the app is fantastic like that! I would personally stick with white doors, but there are so many lovely choices out there!

Your colour scheme sounds lovely and by the looks of it, the project is coming along really well! The best way to consider how much grey to use is probably to consider lighting (daytime and in the evening). If you have lots of natural sunlight and artificial lighting for the evening then I'm sure you're onto a winner with the grey! Good luck!

The only way you can be sure of which colour will work with your cabinets, is to see the actual tiles in the space. So if you can, get samples out and lay them on your floor against the cabinets. If you have to choose between those two, I'd go for the dark one, but that is just because I think that light grey is such a cold colour and it's hard to say if it works with your cabinet colour. The dark tiles will make the space darker though. If you can go for another option, I think Jules' idea of going for a wood look tile is better.