Single Post Template adds the ability for your theme to include "Post Templates" in much the same way you can add "Page Templates"
Please see the Installation -> Usage section for details on how to create new Post Templates.
Please see the Installation -> Usage section for details on how to use Post Templates.
Yes. Source credits for the plugin should remain intact, per GPL requirements.
If you don't know how to do this, you will need to contact me for instructions. I do charge a consulting fee for this service.
Because I try to offer personal email support, I do ask that you compensate me for the time I spend helping you. This can run anywhere from $10 for simple support, up to $125 for more complex issues or use cases.
Bug reports are, of course, appreciated and cost you nothing. I will try to make sure bugs are fixed ASAP.