Well, every rotation is inherently three-dimensional. Look at this picture (
http://exploration.grc.nasa.gov/educ.../rotations.gif ) as just one example. Every rotation can be thought of as having all three components in the picture. Though if you had a pure sidespin, two of three components would be set to zero. In this case, spin still has three components (short reason, it is a 3-space-dimensional universe), it is just that the value of two of the three components are zero.
Centrifugal force is just a fictitious force used in rotating reference frames. In the 'real world' it doesn't exist. That said, centrifugal force has nothing to do with a ball in flight.
Gravity, Lift, and Drag forces are the forces that affect a ball in flight. Lift is highly dependent upon spin, and drag to a certain extent.
I should probably mention that the way I use 'lift' is not just restricted to opposite of gravity. For example, hold a single piece of paper vertically, and drop it. It will rotate and be pushed off in one direction or another. This is the lift force on the side of the paper pushing it to a side. Sometimes people will discriminate between the anti-gravity lift and a sideways-pushing lift and call that sideways lift yaw. (Depends a lot on what your background is.)
If the ball had a denser spot, the spin could change and hence the lift force could change significantly pushing the ball in a different direction. As far as I know, this can only happen if the denser spot was in the original plane of rotation and then goes off it, or if the denser spot was off the rotation plane and then got onto it. A small gust of wind would be enough to change the rotation to move a denser spot on or off plane. Also, all other things being equal, the denser spot will eventually move so that the denser spot will rotate on plane, though I do not know if there is enough time for this correction to happen in the time of an average golf ball's flight.