You can give extra holding power to a worn out screw hole by breaking off toothpicks and stuffing the pieces into the screw hole. It should allow the new screw to have the holding power needed to keep the hinge attached to the door or frame.
Bumper pads are used to reduce the noise of the door hitting the frame (and protect the wood too). You can buy bumper pads in a variety of different materials, including plastic, felt or cork. Most are simply peel-and-stick and can be applied to the corners of the door.
Often, dowels are used for easy installation of a concealed hinge to the cabinet door. If you are replacing the concealed hinge, leave the dowels in place and use the same screws to screw in the new hinge. The screw forces the dowel to expand and keep the hinge tight on the door. If the hole pattern doesn't match up with the replacement hinge, you may need to use a new wood screw to affix the hinge to the door.
Many hinges have a pre-determined overlay measurement. Overlay refers to the distance the edge of the door actually overlays the side of the cabinet frame. Hinges that are marked as "variable overlay" mean that the hinge is screwed in directly on the face of the frame, so you can have any overlay you want.
Sometimes concealed (or hidden) hinges are referred to as "European" or "Euro" hinges. These hinges typically refer to a cabinet frame that doesn't have an extra piece of wood used to create a face frame border. Another term often use is "Frameless" concealed hinges because they are used on frameless cabinets. Cabinets with a face frame can also use concealed hinges. These hinges typically attach to the face frame itself. These are often referred to as frame or face-frame concealed hinges.