1 How to find out what SQL is currently running by particular session ?

There are at least 2 ways to find out what SQL is running by particular session. DBCC INPUTBUFFER and DMV.

DBCC INPUTBUFFER( Session ID)

Use sp_who to find the session ID. Then run

DBCC INPUTBUFFER(148)

DMV

Find the SQL Handle

Select session_id,status,command,sql_handle,database_id

from sys.dm_exec_requests;

select session_id,txt from sys.dm_exec_requests r cross_apply sys.dm_exec_sql_text( HANDLE) 

where session_id = id;