Painting fireplace & trim?
The first question of trim "matching". You are right in trying to coordinate all the room colors. They don't have to match but they can't argue. It is about blending or standing out. If the fireplace is the focal point then it should be a different color than walls and trim. When you paint trim it can blend or stand out. When you keep the wood color that frames it. If you paint it the same color it goes away. Then of course is any complimentary color, like deeper cream or green. I just painted an exit door of a room the same color as the walls because I want the fireplace (feature, focal point) to stand out. Crown moulding is another feature, there are formal and informal choices. It is an architectural ehancement, how you design the decor can soften and warm the feeling of even a grand/architecturally formal room. The cottage style, beadboard, flowers, comfy fabrics- often has crown moulding. It is the other furnishings and fabrics (texture) that sets the mood from formal to casual. Post pics or be real specific and I can give you my opinion if you want it. Basically, you know what you like, work them together and use basic things to make them cohesive. Like color or fabrics or a certain style. I hope that helps.