On your paint problem I can't be much help. This usually happens because of damp -- please get a damp expert to make sure that there isn't any damp lurking in your walls. I had this once when I had pipes leaking inside the walls. I didn't know that. The other alternative is something like painting before the plaster is dry or some kind of chemical mismatch. I do know you will have to scrape all the mucky powdery stuff away and start again, at least on those areas. Don't try to seal and prime and repaint until you know exactly what the problem is and how to fix it.

HI there, Yes, our site can't upload renderings unless they are jpgs or png, so i have converted them for you..

hi first fix the tile on the ply using epoxy chem leaving groves to be filled later with epoxy grout fix the ply with tiles on celling with fastener and then apply epoxy grout to fill the groves later left

u can play with any colour... but the cut out made on plaster has to be dark colour Rest Light Colour also any moulding on plaster has been made has to be in dark colour....