there are plenty of 3rd party products designed to monitor and even block USB sourced apps and files. The USB is a major problem as far as protecting enterprise systems because we as administrators have no control on the source or creation of the data. I can simply browse to your machine using local tools and see what files you have open. Use your work computer for work, and if you feel the need to run an unapproved app, beware the consequences.
Yes, it is possible that you USB flash drive could be monitored provided that the network administrator has installed a software specifically to monitor any devices plugged in to the network computers.