I would advise using a block on the back end of your sacrificial fence to align your work rather than using the fence itself, and that the block is clear of the front edge of the blade. Kickback can be a bitch, even with a dado cutter.
The sandpaper on the miter guage is a great one too.
the little guy
If the blade-to-fence-to-miter gauge has been properly aligned, a non-through cut is unlikely to kick back when using the fence as a reference. Poor alignment is another situation altogether and it won't mater WHAT kind of cut you are making, bad things WILL happen.
Pulling a non-through cut BACKWARD over the blade after making the cut is the most likely time for bad things to happen in a non-through cut. After making the cut, pick up the workpiece clear of the blade before sliding the gauge or sled backwards. Same goes for a through cut.
The piece that is shot directly back is one that is trapped between the blade and the fence because it can ride up the fence as the back teeth grab it. This lets the whole piece get on top of the blade and fly. The piece on the outside will be thrown more to the side unless you have something rigidly blocking its movement to the left.
Adding the sandpaper to the miter gauge is a good idea. The spacer block is required for through cuts with a miter gauge where you want to use the fence as your reference stop. As Tiny said, make sure that the spacer is positioned such that as the material enters the blade, it has completely cleared the spacer block.