Do You Need A Lot Of Knowledge For VPS

I've run a Linux box for ages with a local web server. Okay, it's not set up like a proper full-on web server but I understand the basics of Linux.

I have a couple of shared accounts and need to upgrade the requirements so am looking at either reseller or VPS (Linux). I know VPS is in essence like a dedicated server. If you pay a hosting company for VPS is the onus on you to do more than you would for shared or is it just that you have more control (installing third party apps, compiling from source, etc)? Do you need more expertise? Is it still usually done by cPanel?

Do the hosters still handle things such as spam, firewall set up and virus protesction?