Go to the map in the bottom right hand corner and go to the Retail Office. It will automatically pop up a screen and you can choose to upgrade your farm.
One reason people visit your farm from marketplace is so they can find out what kind of crops you have so they can ask for your harvest. Another reason is so they can get ideas for their farm.
Yes you need ifile with a jailbroken iphone Go to: Ifile then,mobile,applications,go to home and settings and change it to view names,then click on farm town,and then documents,continue to click on...