I'll start with the cold, a vaporizer is always great no matter how big or small a cold is, if she is having a runny nose, stuffed up nose ect,....a little over the counter meds are fine just ask your Ped for exact dosage, Dimetap(SP) is best for that issue, coughs can be helped with the vaporizer, whithout more info it is hard to give more suggestions.
To your hubby, I must admit mine have fallen off the couch quite a few time in their little lives....poor things. I have 7 and number 7 would only let you sit him propped up on the couch, if your couch isn't to high, which mine isn't then she isn't really going to get to hurt just really P.O'd. Here is a trick a friend taught me with number 5, if your couch has cushions prop a pillow inbetween the outer portion of the cushions, this prevents the baby from rolling over and falling off, even when they are a little older and roll better, don't prop it to high just enough to give a little lift. Next, if you don't already have one go by a bouncy chair and have him place her in it, when he intends to leave the room, the vibrating ones are really good.
It seems that he is still a little nieve when it comes to babies, and this is probably his first, so he may not have all the skills down, so if you can find a way to redirect him with out making him feel bad he will probably be more willing, also lead by example, if you use the couch, he will, if you use a bouncy seat or swiing he will be more likely also. Good luck it will work out!