Shared Hosting is enough for me, I want a server, but which one to choose?

Questions of our new client:

Another lie from the shared hosting provider made me think about “how can it have its own dedicated virtual server?” 
I myself am an IT person, but I turn to Linux in extreme cases only if the operation cannot be done on Windows . On Virtual Box I set myself CentOS 6.5 and from time to time I run something there for tests, but I don’t imagine what hosting providers offer for virtual servers. 
So far I have decided to go a short way to the cheapest tariff plan VPS1. Among the options there is an opportunity to put CentOS, but it is not described in more detail what this means. 
As far as I can imagine, I will have to work exclusively with the command line without any graphical shell. Or do they have some kind of graphical web interface? This is the first question.
And second, what can such a server withstand from 512 MB of RAM? At least tentatively that the intensity in the requests per second, if I plan on it to put Apache + PHP 5.6 + KohanaFramework (a bit heavier in the framework resources than Codeigniter).


Yes, Centos is linux OS and is controlled from the command line, but this does not mean that there will be no graphical shell. There are many specialized shells available for managing sites and server through the web. Basically, they are all intuitive, some are paid, but there are also free ones.

Server management through the shell is quite simple and does not require specific skills, and if something is not clear, then there are lots of instructions for working with one or another shell. For our customers we can install any free or help with the installation of a paid console. For example, the free Vesta console demo version can be viewed and evaluated for convenience on the website, which is quite easy to use.

The answer to the second question is not so straightforward. After all, an assessment of whether the server draws with minimal parameters or not depends mostly not entirely on the software, but on the number of visitors who will use it. Nevertheless, the simple nginx-apache-php-mysql site will work with minimal configuration, quite well. As for the rest of the software, the manufacturer’s recommendations state the minimum amount of resources required for work.

When you do not know the answer to your question, you can always contact support for clarification.