moth orchids not performing

First, the simple question: Yes, it is likely the plant with the broken leaf will continue to grow new ones.

The silvery coating on the roots is velamen, which acts like a sponge to soak up water. The roots should turn green when you water them.

I'm not sure why, but I get the feeling you've succumbed to "overwatering kills orchids" thing, and are not watering enough. The key is to keep the potting medium evenly moist, witouth suffocating the roots, as orchids do a great deal of their respiratory gas exchange through them, rather than leaves, as is the case in terrestrial plants. Moss can be a tricky potting medium, as if saturated, it will hold so much water that is does suffocate the roots.

As to reblooming, you need to understand the life cycle of the plant. Phalaenopsis, for the most part, thrive in high heat and humidity, in fairly deep shade. In order to bloom, however, they need to experience a period of about ten days to two weeks in which the average growing temperature is about 10-15F cooler than what they had been experiencing. For most home growers, that happens naturally in late autumn, with flower spikes emerging size to eight weeks later.

Go light on the fertilizer. Of all of the parameters of orchid culture, it is probably the least important. Yes, they need food, but not a lot, and "more" is more harm than good.