I never feather any finish plaster and as for radiators I always request that they are taken off the wall. If customers wish to leave the brackets on the wall I have no problem plastering round them. For plastering round akward places I have a selection of small contractors tools e.g small tool, margin trowels, pointing trowel, gauging trowel, migit trowel and sponges. These normally get in the tight areas but I will always try and get a finishing in a space where it fits as this produces a better finish than using the smaller tools. I always make sure that awakard areas get well pva'd so that I have time with plastering around things, I also like to use the sponge float around awkward spaces as it helps to keep everything flat and leave a nice finish. Bathrooms are the rooms I hate where you get asked to plaster round sinks, toilets, wastes, pipes, baths, built in shelving etc, etc! Bloody nightmare jobs, but its work I suppose so won't complain, much! For those narrow areas down the sides of internal doors I always apply the plaster with my margin trowel or small tool and then use an old one inch decorators brush to brush the plaster up and down as this evens the thickness out. when trowelling up, I alternate between say the brush and margin trowel and the last trowel is done with the margin trowel. This method works well with me. Hope this helps