I think the important thing with your choice in fertilizer is to avoid the urea based nitrogen unless you're dealing with the truly terrestrial bromeliads. It is my understanding that with epiphytes this type of nitrogen is useless since it needs the bacteria in soil to break it down into usable product for the plant.

I always make 12 collages from our year's photos and take them to Kinko's to be made into a calendar. It is an annual gift to DH, the family photograher and is a great way to save the best pictures, so they are easy to find! We hang it on the refrigerator with magnet clips, so we can enjoy the pictures on a daily basis. So much fun. Wish I had started the tradition when we first were married. I do try to get the animal calendars to distribute to my students-they love the World Wildlife and SPCA ones.

One of the nice things about paint is that it's relatively inexpensive - if you don't like it or the future solatube doesn't flatter it, change it. Having said that, I'm having doubts about your color scheme. You're describing a white/near-white room and fixtures with one dark element, the vanity. Even the towels are vanilla. Have you found a shower curtain that picks up on that expresso? Dark framed mirrors or wall art? Washcloths? If you have those dark elements somewhere (hopefully not all on the same wall), then you're probably OK going with a soft white on the walls. Choose one that looks good now and change it down the line if it's not so good with the new solatube. As far as choosing the "right" white, see if your paint store has trial size cans and just paint a swath. Failing that, collect up several color strips of the color you might like, cut out the one you want to see from each strip and tape 9 or so color squares to the wall to see what it looks like. P.S. As long as you're trying out whites, why not make a patch of red or another bold choice and see how it looks on a wall or two? You never know.

One valve and a diverter means that you can only have water from one shower head. A diverter is what you have with a bath tub / shower where you choose to have the water at the tub spout or shower head. I believe this would be the lower cost option. With two valves you can have water from both shower heads simultaneously. But then, you would have to adjust the temperature of each. How do you intend to use the two shower heads?