A small amount of resin is normal for the first couple of regenerations, it should stop after that. You should check the dlfc button is installed correctly, and that the right button is included with your system. Also, take the temperature of the water. If it is below 65 degrees, you may want to look at dropping the DLFC size slightly since you dont have a top screen, or add the top screen.
When removing the valve, kepp turning the valve back and forth, do not just pull it straight up. This will minimize dthe risk of the manifold coming out of the gravel bed. Also, do not put the system into backwash before removing the valve, this will keep the resin and gravel packed down which will also help to keep the manifold in place.
A 10" diameter tank should have a 2.4 gpm button, a 12" tank should have a 3.5 button assuming your water temperature is not too low. Can you give us more information on your system?