use a rattle gun to loosen nut.anti-clockwise .its just too easy this way.
as for the big metal thing its a tapered sleeve on a tapered shaft and sometimes its very tightly on there.use a puller.if it wont budge and you are going to replace the bottom seal anyway you could heat it up.it will expand on the shaft and come off easily but you will probably cook your seal so try a gear puller 1st.
