Common function to check if an element exists
You shouldn't even need to do a check for element exists before calling a jQuery method. All internal methods, and any plugin that follows good practices, just won't do anything at all if there are no elements in the set. So you could just simplify that part of the code down to (without the if):

$('.iCheck').iCheck({
    checkboxClass: 'icheckbox_minimal-blue',
    radioClass: 'iradio_minimal-blue',
    increaseArea: '20%' // optional
});