If so, what's it like as I'm told Joomla will run on it no problem, as with my current shared hosting but having looked in to CentOS, I'd need to install LAMP server first, isn't this not disimilar to WAMP and the like that one would run on a local machine, but instead it runs on your live linux hosting server?
Usually the webhost will set that up for you.
I am told by my hosting company that even with the basic VPS package, it will still be an increase on my joomla sites performance compared to the current with being on shared hosting at present, would any of you agree?
Yes.