The roughnesss on the top of the part is most likely contaminates in the bath. If you could run the bath through a coffee filter every 2nd or third day of plating it will help a lot.
The pitting is probably one of two things.
One, your metal (copper,steel,nickel) that you are plating onto has small pits in it to start with. If it is copper you are plating on, hold it up to a florecent light and also a incadesent light to look for pits prior to nickel plating. Nickel will accent those pits and not hide them.
Two, the PH of the bath may be too high. You may have to lower it with some battery acid. Find out what your PH is suppose to be for your bath and get some PH papers for checking it. Nickel baths tend to rise in PH with usage. Small baths are especialy prone to do this.
The blistering is most likely the surface preperation prior to the plating. Clean...clean...clean!!!
Try using a alkaline cleaner along with your degreaser
Good luck
48 Buick