All of these features may look impressive, but if you don't know what Dedicated Hosting is in the first place, these features probably don't matter much to you at all. When you purchase a Dedicated Server from A2 Hosting, you are getting all of the resources listed with the server plan of your choice. You do not share these resources with any other user or customer. The bandwidth, RAM and data transfer are for your use exclusively. With all of these resources at your disposal, you can expect your hosting service to be both highly reliable with top performance.
The answer to this question largely depends on two factors. Are you new to server technology and not very interested? In this case, Windows is the easiest option to get where you want to go. Do you already have experience with Linux or would you like to familiarize yourself with this operating system? If so, Linux gives you more freedoms to configure your server, and you will be using an operating system that is less vulnerable to attacks from the Internet. Linux is also open source and therefore free.