I read through some of the other posts but I still haven't found any information on whether or not it is ok to replant while it is flowering. So far I have moved it into the bedroom where I leave the shades open all day so it gets lots of light. Since the first buds fell no others have started to shrivel up, so I guess it was just a blast from the cold in my apartment, but it seems to have settled in now. I am still concerned about the pot though, since it has no hole in the bottom. Can anybody tell me if I can replant it now, or if that will destroy the flowers currently in bloom?

The mildew you are talking about is probably algae. You can tell because of the green color. Mildew or fungus is often white or grey. It is not in the plants best interest to trim the roots because of the algae. The plant needs roots to uptake water and nutrition. You will be surprised at how slow the roots grow. That's a great choice of orchid for a beginner to keep in your house of apartment. Just keep it out of direct 10 am to 2 pm sun so it won't sunburn. I usually water mine inside every 4-5 days in the winter. As it gets warmer in the spring you will want to increase watering. Your goal is to let the potting medium just come up to dry before you rewater. Have fun with your new babies.

Not that I have personal experience with this particular stapelia, but I believe when they are in a growth period, they need more water. Otherwise, you'll experience bud-blast. I also think your Huernia would enjoy more sun/more heat. Are you able to put it outside? Good luck with it!

Do not know if Mineral water is OK. Water from the tap is fine as is rain water here. Plant needs bright light but screening from strong direct sunlight is necessary here winter and summer. You need to find some complete culture notes written for Climates similar to where you are in Pakistan. Plant looks in reasonable condition. Culture notes prepared by the American Orchid Society are in the link. AOS Phalaenopsis Culture Notes