Is there a way to control Subscriber callback frequency while using rospy.spin() ?

edit

let's say, we have a Subscriber node that looks like this -

#!/usr/bin/python 

import rospy
from std_msgs.msg import String 


def callback(data) :

    print "Inside callback: " , data 

if __name__ == '__main__' : 


    rospy.init_node('test_subone')

    rate = rospy.Rate(1) 

    s1 = rospy.Subscriber('/test_topic' , String, callback, queue_size = 1)

    rospy.spin()

I have set rate = rospy.Rate(1).

Does this influence the rate at which the Subscriber s1 calls its callback function ?

Is there a way we can make rospy.spin() to achieve this?

Is the rate at which the callback function is called only dependent on the rate at which /test_topic is being published?

What happens when there are more than one Publishers publishing on /test_topic at different frequencies?

Are things different in case of rospy and roscpp?