10's down to 9's will be a breeze, you shouldnt have to change saddle positions or intonation, but sometimes it happens. You may have to adjust trem spring tension a bit to keep the bridge level with the body
Once you get the new strings on, tune to pitch, then stretch each string, then retune to pitch again.
Repeat 3 times.
With the strings tuned to pitch, check the bridge to see if it is level to the body. If the back end is too high, loosen string tension slightly and turn the trem claw screws into the body 1/2 turn. Retune to pitch and check for level again. Repeat until bridge is level and guitar is in tune.
If the back end is too low or close to the body do steps as above but turn the claw screws out 1/2 turn at a time.
Check intonation once in tune.
Have fun.