My school has one of those super overreacting web blockers (specifically Fortisnet) that blocks things that should be accessible by a high-school senior trying to research projects. Despite many students' complaints the administration's hands are tied due to parents' complaints.

I have setup a VPN account from http://www.vpnreactor.com. With this I am able to bypass the blocker. I know this service hides my IP from websites and servers on the web. I also know that the school pays an IT guy just to monitor sites and network traffic that the students are using. Basically, will he be able to see my network traffic? More importantly, will he be able to trace it to my computer or its MAC address?

I am connecting over Wi-Fi, not ethernet.