What year and model (GT or GTP) is your car. Aside from that, yes, you can do all of that yourself. There is plenty of writeups here to replace the LIM gaskets and the other parts that go with it. Oil pan is a PITA (have to jack the motor up a bit). Brake and fuel lines can be done. Rocker panels (depending on your welding and body work skills) can be done as well, minus any paint.