The other question was what were they (or particularly the impatiens) potted into? Is it a commercial potting mix, something you mixed up..? For the begonia, using garden soil in a potting mix is not a good idea especially if it was not heat treated. Firstly because a potting mix needs to be more airy, and secondly because garden soil may have disease organisms in it. Drainage is still better to have even if under-watering. Yes cold, dry air and drafts can negatively affect plants but some plants are more tolerant than others. For the New Guinea the pot looks rather large for the size of the plant but it's hard to tell from pictures what its problem is. It actually doesn't look too bad in the pictures. I may have the wrong impression but it seems you do quite a bit of repotting?
