You can install EPiServer 6 r2 on Windows 2012 running by SQL 2012. However there are few manual steps to be taken. More details - http://dotnetcake.blogspot.com/2012/06/installing-episerver-6-r2-on-windows-8.html
The latest from v6 version EPiServer Framework in NuGet feed is 6.1.379.0. From experience - when upgrading NuGet package within the same major and minor versions (like 6.1 or 6.2) code changes needed is really low if any.
I just tested and confirmed that installing and running CMS 6 R2 (6.1.379.1000) on SQL 2012 works fine (didn't try Windows Server 2012 though).
Beware that when installing a new CMS 6 R2 site through Deployment Center, your web.config will get the "old school" (IIS6) format, i.e. sections will be named "<httpModules>" instead of "<modules"> etc (overview: http://world.episerver.com/Documentation/Items/Tech-Notes/EPiServer-CMS-5/EPiServer-CMS-5-R2-SP1/Changes-Between-IIS6-and-IIS7/)
To run your CMS 6 R2 site on IIS7 or higher (Windows Server 2012 uses IIS 8.x) you would have to either migrate your web.config file to the newer format or run your Application Pool in Classic mode (not recommended).
In addition to the link that Valdis posted, you will likely also come across this problem: http://www.epinova.no/blog/arild-henrichsen/dates/2013/3/fixing-the-assembly-redirect-for-file-powershell-bug-for-episerver-6-in-windows-8/
(This will apply if you manually download and install the latest CMS 6 R2 patch. If you install via Nuget you will avoid this problem, just make sure the assemblies from the nuget package actually have the latest version 6.1.379.1000)
Thank you for your replyes! I appreciate it.
I will try to instal it on a windows 2012 r2 server see how it goes.
I have several questions about EpiServer 6 r2. In our company we are running EpiServer 6.1.379.0. My questios is;
1. how difficult/easy is it to upgrade it to the latest patch (i think it is 6.1.379.1000 ?) - Do we need to do a lot of code change or is it just to run it?
2. Do EpiServer 6.1.379.0 support sql server 2012 or is this not supported?
3. Can we install Episerver 6.1.379.0 or higher on a windows server 2012?