As a whole how customisable is wordpress? Like in order to develop it into websites such as: http://www.tech.co.uk/news http://www.pcpro.co.uk/ http://www.pcw.co.uk/ Etc?? Or would I be better off having a whole site backend system developed. Also if I wanted a new site system to replace wordpress would this be something I could have done by someone within losing links and without losing all the content or would I need to go through it all over again?
There are a TON of Word Press Themes (Paid) to choose from that will exactly what you want. I personally prefer it to a static website. What you are looking for is a Magazine Theme, or something like the one I am building with "remix", here. It's mostly static website, with blog embedded, and differing home page options.
Wordpress is pretty how. But some of the big names use Joomla. Theonion.com and LedZeppelin.com both use Joomla as their back end. But quite honestly, it is easier to add stuff to wordpress
I am talking more backend wise as well. So would it be possible to add lots and lots of features to the wordpress backend to manage all site content from one location?
have a search of the plugins and add-ons that are available for wordpress before hand, that way you know what is and what is not possible.