Getting full access to the server is beneficial as well as harmful also. You can mess up all setting by mistake if you have full access. You cannot do such stupid thing in Shared Web Hosting U.
Linux web server is very well-known that capable of running hundreds of tasks at the same time with stability. But it doesn't mean Windows web server is bad. The right term would be like this; Linux can max out server capacity but windows can not. So web hosting company maybe do this: 400 shared hosting account if using Linux and 350 shared hosting account if using Windows platform.
Affordable Web Hosting company should provide a unlimited domains and unlimited sub domains hosting. Well, if you are not going to host more than one website than it is fine to select hosting with limited domains hosting but it should at least provide unlimited sub domains hosting. Most of the hosting companies provide unlimited domains hosting.
Below are a few more but I could go into great detail and do not want to confuse you. If you have the time, look into all of them by using your favourite search engine and decide which is best for you.
Get into Shared Web Hosting UK 2.0 (aka Social Networking)! Start a blog (you are reading an example), post a video on YouTube, set up a company page on Facebook, post press releases online, write and post articles about your area of expertise...The possibilities are growing all the time and the more work you put in the better the results you will achieve. Don't forget to link everything back to your site!!
Will they hold your domain to ransom when you come to transfer away? Can you be in full control of your domain at all times? Is the company just another reseller of a reseller of a reseller?!
Finally, when you choose a host - always think that it is the best friend of your site. When you make a friend in real life you always consider lot of things before choosing and also overlook minor mistakes to keep a long term relation. A web host is a real friend for you as it provides your business keep running online 24 hours a day and 365 days a year.