in or out only matters if you are 1. getting ready to sell 2. trying to impress a sister in law. that said, i think they are most effective when they have no openings or symmetric openings with the bed centered. otherwise you'd just be highlighting an awkward wall.

As long as the correct wall is chosen to be the accent, it is fine and can be very cool. Here is a nice article about which wall to pick. https://www.thespruce.com/dos-donts-of-feature-walls-2213473 While there are exceptions to every rule, these are usually true: Accent the headboard wall in a bedroom, accent the focal wall in a living/dining space (this is the wall your eye is naturally drawn to in the room). Not many kitchens benefit from accent walls (there is already a lot going on it a kitchen), bathrooms/mud rooms/laundry rooms are usually not ideal places for accent walls (due to a lot going on and the rooms are generally small). The exception to this is a guest/half bath sometimes can be a show piece with an accent wall.

Tough to say without seeing the whole place, but if the windows are the focal point in the room, I wouldn't paint anything that stands out, and likely would match to the white. I think you should draw attention to the window area of the room and not highlight other walls, it could look too mish-mashed.

Chalk markers are a way to get around the dust. For a rental, I would probably leave it. Write up something cutesy on it for potential renters when the house is being shown.