"Loads of tiny flies" are most likely fungus gnats. Reason for them being there is moist soil, that probably contains lots of organic matter.

"White fluffy dots" sound like mealy bugs, but need clear photo to be sure (could be something else).

Go to the big box store and get some house plant insecticide. Sounds like you may have a water problem. Keeping them too wet.

Air flow is another important factor.