Airplant care for a newbie?

Attached are some pics of some airplanes I’ve had since midseptember. I could use some advice on how to care/better care for them.

Here’s some room info and my routine based on some web searching.

Room has no windows – just fluorescent lights. A grow light is not possible to have right now. Temps are around 70°-71°. Humidity 40-45%. I soak for 30min once a week and mist daily.

1. How are they looking? (And what is the white stuff on them?)

2. What am I doing right?

3. What should I stop doing?

4. What should I start doing?

Thanks so much!