Question 1&2 - These items are listed for future releases as a project. Date TBA
In regards to discounts, all these can be done by Automation Commands, and Order Tags. Look through sambapos.org as there is documentation on this.
Adding a button to clear SQL data is very dangerous, thats why we clear data the hard way so accidents don’t happen. You can look here for a script I use http://forum.sambapos.com/t/zero-all-accounts/511
Custom reports again has been listed in future projects.