I think we think more information, such as the table structure including the indices and the execution plan to provide good suggestions.

Execution plans shows sorting takes the longest. Can you or anyone else please answer my question#2

I would say it really depend.  What columns are returned, what columns are used to constrain your query, and order do you want your data returned and grouped.  Potientially a new covering index that has only a few indexed columns and a number of include columns would perform better.   

If you doubt on the indexes then you could take help of PROFILER and INDEX TUNING WIZARD, also try to wrap up the process with a stored procedure for maximum efficiency during the execution, as you will observe difference in processing the query within QA and from reporting application.