Why not a big pane of glass for the anteroom door with top and bottom rails and the stiles the same as the paneled doors. Three panel on the closet doors instead of six because of the narrow width. Proportion trumps number. The windows on the top stories of many period houses with 6-6 sashon the lower floors, are 3-3 with a proportion similar to the lites below. Some have been replaced with 6-6, resulting in a cluttered window with horizontal looking lites. Proportion is more important, and the width of those panels if you did 6 on such a narrow tall door would be sliver-like.

In our last house the powder room had about the same sqare feet as yours does, just different dimensions. We had three halogen lights above the mirror and that was plenty of light for everyday use. I don't remember the actual bulb we used as we haven't lived there for almost a year. Just look for sconces that allow a brighter bulb or that use two bulbs in each sconce. I would use the lumen formula davidtay posted above. That will help you decide if the sconces you like will be bright enough. We did have a bathroom fan with a light installed above the toilet. That helped for when I wanted to clean the bathroom, or needed a brighter light for removing slivers, etc. as the bathroom was where we kept our first aid kit, but we could have gotten along fine without it as the light from the vanity fixture was enough for the room.

With that width the most expensive item will be the rod. If she wants to save some $$, she could buy a closet rod from Home Depot and have it cut to length. Then paint, or stain it, add finials on each end and use some rings with clips to hang her curtains. She could use the bracket linked below, and for her curtains buy some sheets from Tues. Morning (or any other discount store) cut to length and use fabric glue to hem, if she doesn't sew, and then hang the sheets using rings with clips. If you catch JCP during a sale she can save even more. Home Depot & BedBath&Beyond also have good prices on rings etc. Also check out: http://www.countrycurtains.com/ Here is a link that might be useful: JCP

If you want the window as uncovered as possible during the day, I would look into shades that you can raise during the day and lower at night. If you are fine with having some of the window obscured during the day, I would consider Silhouette shades. The sheers protect the interiors from UV light and help bring natural daylight further into the room. Shutters would be a nice look, but I'm concerned about opening and closing the louvers. I'm assuming since you want privacy at night, you will want to keep the window treatments closed at night. If the sofa is going to be sitting in front of the window, you are going to constantly be reaching over the sofa to open and close the louvers. With Silhouettes, you can get a similar look to the shutters, but you can operate them with a cord (which can be placed on the side of the window that is most convenient to reach) or they can be motorized. Silhouette shades also come in wide widths, so you should be able to cover that window with one shade.