The functionality to turn quad into fan is called Poke, select a quad (or more) and press ALT+P ( or CTRL+F -> Poke Face )
For the model, splitting the arms/legs from torso, do you mean you want arms/legs as different object from the torso ?
If so, select the arm or leg then press P -> Selection to make what you selected as a different object.
If you want to separe the character and the cloth into being different objects, select the whole character, move your mouse next to it and press L then you can press P to make the character as a different object from the whole cloth.
Note : if you want to merge 2 objects into 1 , in Object mode select objects and press CTRL+J
im going to be remapping the UVs on the “tights” to make creating a set of dancers clothing so im going to be jig sawing the map but i need a clean set of faces to work with. Will be printing this out for reference.