I have had extension built which is near completion. I am wondering how long I need to leave the new plaster before I paint it? and how many coats of paint will it need? I want a matt look in a neutral natural colour. should I use some cheaper white paint a few times first? also, in the existing house which is old sandstone walls, the paint is starting to take on an eggshell appearance and peeling off in some places above where the radiators are. I did paint this with a satin type paint then painted over it with a matt one. can I just sand the flaky bits and start again? also, on the front wall inside, we were told to get a damp proof course in which we did. since then, patches of black mould keep appearing. what can I use to paint over this (it has stained the wall) and can I prevent it happening again? ( hoping for knowledgable replies so I can shock my dear partner who thinks that my only contribution will be pointing out the colour paint I want on the sample strip!!! )