I am trying to understand how to control several Xbee’s I/O with a single xbee connected to a computer.
One more issue I have is wifi xbee.
For exmaple this module: https://www.sparkfun.com/products/12571
Can I connect to a wifi network and also to xbee series 2?
You certainly can do that. I have just been playing with the new XCTU. I put API firmware on all my modules and then sent a remote AT command in an API frame from one board connected to my PC to another module and had it toggle IO.
Download and install the latest version of XCTU here http://www.digi.com/support/productdetail?pid=3352&type=documentation.
For complete details on API frames see the product manual for XBee ZB modules here http://www.digi.com/support/productdetail?pid=4549&type=documentation.
You cannot talk to a regular WiFi network with an XBee S2B module. You would need an XBee WiFi module to bridge the gap between Zigbee and WiFi.