Well, a big company is supposed to have written policy about internet usage. You should read these policies carefully if you are concerned about privacy.
If they can tell what you are doing?
It depends, surely they can log all the web pages you have opened but in https pages they can't know what are you doing since communication is encrypted. For example they know you are in facebook but they don't know to which photo you hit like. They know you are in reddit, or what subbreddit you have opened but they cannot intercept your messages or comments.
Are they able to connect your ipod to you?
It depends in which way the network is configured. If it is a public network (everyone puts the wireless password and are connected to internet) then they don't know its you, but they can identify that it is a apple device, and other device information which might leads them to you. If its not a public network that means that your device MAC address was preregistred in a dhcp server which release the IP address you have. If its like this than the IT guys surely knows the ipod belongs to you.