The code doesn't really follow the MVC pattern but this is not the point.
What about accessibility?
Last thing, i find the publish/unpublish mecchanism from frontend really tricky when i tried to change its look.
I think instead of planning to add new functionalities (useful for who?) you should concentrate in improving the code, performance and making accessible what you already have done.
PS: regarding accessibility have a think about an audio captcha.
1. This component was developed and at this supports both Joomla 1.0 and Joomla 1.5. Because Joomla 1.0 didn't support MVC I have use my own implementation of templates... However in current implementation the templates they are fully separated from code. And you also can overload JComments template in your Joomla's template. In nearest time I'm going to stop supporting Joomla 1.0 and begin using Joomla 1.5 MVC implementation. I think it would be more correct and more productively.
3. I don't understand what problems have you got with changing look of these buttons.
4. If you've any suggestions about improvement code and performance - please go to our forum and post them in appropriate forum section.
Thank you for your criticism, but do not forget that is always easier to criticize than to do something ;) Visit us on the forum and let's discuss how to make this component better.