I wouldn't run dbol longer than six weeks. It's a 17aa steroid which is very toxic to your liver. Besides, after the 3rd or 4th week, the gains drop off significantly.
You should get decent gains with 25mg/ed if this is your first cycle.
Unless you take anti-estrogen with the dbol, most of the gains will be water. Now that's not to say that you won't gain some nice lean mass, it's just that without an anti-e it tends to bloat most people.
If you run the proper pct, you should hold on to a lot of your lean mass gains (not water weight, lean mass) In fact, to make it simple, you could run 20mg/ed of nolv throughout the cycle which would keep the bloat down. Keep running that for three weeks after you stop the dbol and you should be fine.