Things DBA's get asked during a day on Job

Things people ask to DBA's during a day on his\her Job: Why this query is running slow? Why this query is running slow from app but not from ssms? Why this query is not picking up \using the right indexes? Why this query is using right indexes when running from ssms and not when executed from app? Why this query is running fast as SQL statement but running slow when same query is wrapped as a stored procedure? Why query is timing out and in result application is throwing 50* errors? Do we have proper indexes? Can we create index on this column of that table? How much time will it take to defragment the index? Are index fragmented? Can we rebuild the index now without downtime ? Can we reorganize indexes without downtime ? How much time will it take ? Why server is slow ?(When Backup and Update stats are running) Can you make query use right index but not make use of option(recompile) or any other query hint at the same time? Why people are unable to login ? Why