How to check mssql version installed + install option

Open a cmd and type :

sqlcmd
select @@version
go
exit

Default instance is that you connect just by specifying the server name (eg, MYSERVER), whereas a named instance will require an instance name as well (eg, MYSERVER\SQL2005).

Clients can connect to the default instance using only the host name over the well-known 1433 port.
To connect to a named instance, clients specify the host and instance name (e.g. "MyHost\My_Instance") and the SQL Server Browser service returns the port the named instance is listening on.

Install terminal services and .NET Framework 3.5 on windows server 2008 2012 r2 standard

Open Server Manager (type in start menu to find it) - or Control Panel - System and Security - Administrative Tools - Server Manager
or Right click My Computer - Manage

Server 2008 :
Click Roles - then click - Add Roles
On the Before You Begin - Click Next
On Server Roles - select Remote Desktop Services - formerly known as Terminal Services
Continue the wizard.

To install .NET Framework 3.5
Open Server Manager
 Click Feartures- then click - Add Features
 Select .NET Framework 3.5 

 Server 2012 :
Mange - Add ROles and Features -- same as above
On 2012 you have to specify additional path to windows 2012 dvd