The original plan was to install unfinished HW and have them stained with the rest of the floor.

The ceilings were almost brown, the carpet was full of burn holes and drink stains next to his easy chair.

One of the contractors would re-stain existing hardwood floors while the other would install new vinyl planks throughout the entire home, with one caveat.

Recently I was made aware that she has an oil leak in her car and essentially caused 3 giant oil stains in the parking spots.

Three layers of pee-stained carpet, 2-3 layers of subfloor, frozen pipes, ruined social life later, was down to the crawlspace and foundation and learned that yes, people did occasionally build a house on a row of fieldstones and mortared brick that was set just right on top of the dirt.  

Expect broken cabinet doors/hinges, holes in walls, broken window treatments, stained carpets, and walls that need complete repaint.  

Stain/poly the shelf instead of paint - will last longer,

When you replace them the new ones likely wont' match exactly, age, smoke and whatever will have stained the original.

Paint or stain - match the window trim, match the walls, or contrast. 

You have to start at one end and slowly work towards the other - sort of like putting self-adhesive shelf paper (Contact paper) down, if you have ever done that.The veneers I have seen are just plain wood, so you have to paint or stain them to match what you have.