Do all brushes fit all motors?
 

Thinking about getting a 13t 370 sized sport tuned motor and getting a spare pair of brushes to go with them,can i just get any off modelsport or are they different sized?

There are lots of different shapes and types from the traditional rectagular in stand up and lay down, then there are the round angles ones in V2 motors and the CHeckpoint stype ones. Best tell the model shop where buying them what you have and ask for direct replacement brushes.