>1) Want Free Database Server for Commercial Use
> Having good GUI Tools available to admin.
> Mysql/Postgre/Ms Sql ...?
>
>2) Type of connection to access database
> ADO , ODBC which is best.
>
>3) Cursor Adepter or SPT
>
>Please share your opinion.

I did use MySQL for some projects and I am very happy with its capabilities, especially replication.

However you must realize that MySQL is not free for commercial use, so you can remove that from your list if you don't want to pay for the licenses.