Wow, Bobby lots of questions! First, your plants need a little water every day, and they need to be right up next to the window. Raise the blinds up all the way too. On sunny days they will need more water. Water the soil only, not the leaves. Water slowly until a little bit of water comes out the bottom on each plant. The white stuff on the soil surface isn't anything to worry about.
I'd need to know where you live to tell you if you could put them outside, but anywhere north of the middle of the country, it's too cold at night already for beans. That's a nice bright location you have for them there.
You might have a tiny bit of fungal leaf spot going on there, but it's probably not enough to kill off the plants before your science fair. Keep an eye on it and if it starts up on more leaves, use the baking soda spray.
Your mom's plant is a variegated one so the leaves are supposed to look like that. The one leaf with the brown edges just looks like it might have a little bit of fertilizer burn. You might water them for her once in a while if you're watering your bean plants, too. You can use the fly spray on those no problem if you see fungus gnats. They will come back to your beans if they're hanging around her plants.