OLE DB :: Configuration For VS 2012

Having below setup : (All this is testing environment)

1.One virtual Machine Guest OS is Windows 8 Pro 64 bit in Oracle Virtual Box
2.In the guest I have Microsoft Visual Studio 64 bit Ultimate Edition
3.Oracle 11.2.0.1 on same host machine windows 7 64 bit

In above Visual studio I wish to use Oracle 11.2.0.1 on same host machine. When I adds sql datasource control, Visual Studio is saying for installation of either one :

(A) Oracle Developer Tools for Visual Studio
(B) Oracle client software version 8.1.7 or greater.

So, I downloaded ODTwithODAC1120320_32bit.zip from below link:

[URL].........

and installation run successfully with a message regarding running installAllOracleASPNETProviders.sql after a new installation. My questions are :

1.When I opened command prompt and said sqlplus / as sysdba it is saying ORA-12560.
2.When I says sqlplus scott/tiger@orcl (I created tnsnames.ora) c:app

ishaproduct11.2.0client_1NetworkAdmin with like this :
orcl =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = XXX.XXX.XXX.XXX)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = orcl)
)
)

In above HOST = i am giving IP address of host machine on which this VM is installed and this is also oracle server database machine too, on which I am running Oracle database;

so, after few seconds I am getting, ORA-12154.

How do I connect my orcl database which is running on the same host machine by using above configurations. My virtual machine is visible from other machines as well as oracle database machine too i.e. ping to VM IP is working fine.