Hi juneeb, I think that before you need to address your 4 questions, you really need to deal with your last statement "My phals are struggling and I'm trying anything".
S/H is just another to grow your plants. It's not a magic cure-all. I'm guessing you're fairly new to growing phals, and you need to get your basic culture squared away. If you take struggling plants and move them to S/H, you'll still have struggling plants.
Before moving to S/H, let's get the basic culture squared away. Here's a link to FirstRays that gives a great overview.
First Rays' Free Info
Good culture produces good roots. Good roots produce healthy plants. Healthy plants produce beautiful flowers.
Beautiful flowers are the reason we grow orchids.
Bill