Hi Arvind,
Thanks for the reply. As for your first question about the Form, you don't need to use an Entity, any Structure will work fine. If you have a Local Variable of the specific Structure type, just drag it onto a Form and Service Studio will create the Inputs.
As for the second question about a subcontractor, if the three more inputs are not in the Entity, you can either manually add the Inputs inside the Form, or if you have them in a Local Variable, just drag the Local Variable onto the Form, and again Service Studio will create the Inputs for you.
As for the third question about storing the data, why do you want to store it as JSON? Why don't you use a normal Local Entity (or multiple Local Entities)? You can always convert it to JSON later if you so must, but storing JSON in the database is very inefficient. I would very much advise against it.