I am a bit confused as to which variables should I include in the factor analysis. I have a huge questionnaire which i know i definitely should include to find the factors but im not sure whether I should include the demographics?
For most research questions I would think not. Demographics are typically used as single item indicators whose factor structure is well know (there is clearly no doubt that a question asking what gender are you is measuring gender). The variables that should go into your EFA are those that a indicators of an unknown number of laletent variables. That is questions 1 through 4 you think might be measuring 1 or more personality factors while 5 through 8 you think are measuring 1 or more motivation factors and you place these in EFA to find out.