1) The lower aluminium-like portion of a light bulb is known as screw cap, which is the threaded base of the light bulb that secures it to a lamp. It connects the filament to the base with two soldered contact wires, where the electrical voltage connects to the light bulb.
2) No, copper is not attracted to magnets. Magnets attract to ferrous metals such as iron, cobalt, nickel, certain steels and other alloys. Copper is a paramagnetic substance, which has a non zero magnetic moment of its own. That is why, it is not attracted to magnets. However, when paramagnetic substances are placed in an external magnetic field, they get feebly magnetised in the direction of the magnetising field.
3) Aluminium is also a paramagnetic substance. Thus for the same reason, as said above, aluminium is not attracted to magnets.