This is all
Run button for what? Your bug report is not understandable. We already have the build plugin with run support, perhaps thats what you are looking for.
add button for running script(build,open in browser for different file types)
The build plugin and external tools plugin allow you to do that.
OK,where I should post my request to adding some plugins to pling?And please,send (YOu can use email if it comfortable for you) how works plugins in kate and info how create plugin.