hydraulic clutch help

I bought a 1981 280zx (L28E,5spd) this summer and when I bought it it had been sitting for 3 years I got it running and changed the oil but not the brake,clutch,tranny,or rearend fluids. Now that its getting colder I have noticed that in the morning my clutch pedal is hard to push in and sometimes it wont go into gear unless I pump the clutch a few times. is this from bad fluid? or is this just how a hydraulic clutch works? I also have a curplunk sound from one side of my rear brakes wich goes away when I press the brakes,wich Les Shwabs tore into it and couldnt find out the reason for the sound, they said everythings tight and ok. Any ideas? Could this be due to the rearend fluid that has been sitting undriven for 3yrs then not being changed before I started driving it? any helpful advice would be great. thanx, Marc
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