1.
A mosfet is a building block device. It has 3 pins (maybe 4 if it's a dual gate type). It generally looks like a transistor. It acts like a valve for electrons, similar to what a transistor does.
A mosfet is easily ruined by exposure to high voltage (static charge, or transients generated by coils/relays/transformers that have no snubbing diode).
2.
IC's come in a thousand flavors. They can be relatively simple (voltage reference with 2 pins), or they can be complex (computer CPU with dozens of pins).
Packages can be:
single inline pin (some resemble a transitor/mosfet),
dual inline pin (flat rectangular),
square, with pins sticking out from all 4 edges
3.
Automative... do you mean automotive?
This implies operation from a 12V supply (8 to 18V range, say).
Negative ground (most of them).
Ruggedized.
Built-in protection from static charge.
Wide temperature tolerance.