You can use code stage for formatting the excel sheet any way you want. All you need is Interop DLL. Code stage will allow you to do formatting in few lines.
From my experience, even though the data type is changed I am able to perform the operations as needed. for eg. I have amount column in excel which somehow got casted to Text in BP collection. But still I am able to perform Sum operation on it. If yo...
OLEDB is very powerful if you know how to write queries. This works for Databases and excel, csv etc etc files. Its faster. In my project, we are mainly using it for data extraction from MS Access DB and Excel sheets. Also few operations like Pivot, ...