Save time and buy a VPS or install Debian in a virtual machine.
Using a SSH Tunnel you can view all content unlike most PHP Proxies (To be honest they suck)
FTP and SQL DBs won't help you at all.
So install
Debian (Or Ubuntu)
Install
OpenSSH
Download
Putty Tray
Input
IP and
Port to connect to
YOUR OWN IP, not mine.
Create a new
SSH Tunnel in the settings. Selecting a
dynamic destination.
Save and login to your host.
Open FireFox -> Tools -> Options -> Advanced -> Network -> Settings
There you go, you've bypassed school firewalls.