Ive never dissassembled a freewheel yet, so you have one up on me there.
The best way to remove a freewheel, if you have the splined tool is to:
Place the tool in a bench vice, splines upright.
Remove the bolt or quick release skewers from the wheel.
Place the wheel on top of the tool and gently rotate until the splines engage, and the wheel drops onto the tool
Grip the tyre and rotate the wheel anticlockwise.
This is more effective than using a wrench.
Some guides advise you to replace the bolt to stop the freewheel falling off, this is not neccessary with a vice.
When replacing the tool, grease the threads and be very careful not to cross the threads. The cheap hard steel of the FW will wreck the expensive soft Al of your hub. Use the tool to rotate the freewheel anticlcockwise until the threads engage, then turn hand tight only.
I usually flush them out with WD-40 then drizzel oil into them . Entry point is either end where the two parts rotate.