You'll be fine. It's when you close in the walls preventing air movement is why you need a vapor barrier. I've done this method tons of times and never an issue. If it's going to be a shop why bother finishing the floor. Unless you want to spend the money and epoxy it for looks.

You can use PT for the sill plate if you want but it's going way overboard. The sill gaskets breaks the capillary movement of moisture. You shouldn't use PT lumber inside but it's not the end of the world.

Use High Density Foam attached to the concrete walls and tape the seams. This is your vapor barrier. Now stud a wall up as normal with sill gasket on the bottom of the wall to prevent the wood from touching the concrete. You can insulate the 2x4 walls as well but do not add another vapor barrier (plastic).

The floor is fine as is.