Hi Sandeep,

If you have some known Inputs and Outputs you can use ANFIS to create your fuzzy sets. If you proceed by observations on real life you need to make your criterias as clear as possible to construct your Input fuzzy sets. The number of membership functions depends on your parameters of input-output. Could you give more details? it could help to answer your questions.

In your survey, whatever the attributes you wish to discuss to be treated into fuzzy. Make an appropriate statistical analysis to fix membership values for those attributes. 

You can select these arbitrarily. Be careful that membership functions are fully covering the universe of operation (range of operation) at all time