3) Event parameters is the information about the event and is provided by the system while function parameters is information a function needs to do its job; the programmer specifies parameters.
4a) The defined variable is dotSize.
4b) You define it by insert a number variable. After it is defined, you will see two blocks: (set) dotSize and (set global) dotSize.
4c) Because the color variables are already provided.
4d) Variable is a named memory cell that can be changed. It is similar to a property in that they are both memory cells, but is different in that a property is a predefined data for a component.