Linux Apache Plesk Server Administration Assistance

I\'m a freelance web designer/developer running a dedicated linux server hosting several not-for-profit organisations. Because I opted for root access and Plesk control panel options it seems I forfeited the right to full technical support from the supplier, and I have come to realise I\'m a bit out of my depth as a server administrator. There are no current urgent problems, but I need someone willing to provide adhoc support to help with maintenance and updates, and also to be available for fire-fighting any problems that may arise. Initially I\'d like someone to review the current state of the server and to recommend any work that might be required. I also need advice on a variety of issues such as backup strategy, SFTP access, SSL certificates etc.

Server details:
CPU - Intel Xeon X3220 2.40GHz
OS - Linux 2.6.24-24-server / Ubuntu 8.04
Plesk - 9.3.0