Those babies with colds will have more trouble breathing after feeds as the stomach expands and presses against the lungs making it literally harder to breathe. The solution is to feed little and often. Which is a pain for those of us who had a decent rotine going, but an ounce or two less per feed and bringing them down to two hourly or so will help with the breathing. Tilting the mattress is also important. Tey will sleep better too, so their health and your sanity both benefit.
The saline things you can squirt into their noses. If you lie them on their side and squirt into the top nostril hard enough for it to come trickling out the other nostril, then wipe whatever comes out away. Same on the other side, and should be done before feeding otherwise they will be sick. What doesn't come out then should come out over the next hour or so as it will make them sneeze, which is the most effective way for a baby to blow his nose. You can buy equipment to clean their noses, a kind of straw with a filter that you can suck the snot out if you want to give a helping hand, but it isn't necessary normally.
Keep an eye on their temperatures and get medical advice if they go over 38 degrees. Add 0.5 degrees to an under the armpit reading, the thermometer up the bum is most accurate.
Hope this helps someone.