I am really sorry for the delay of this reply as it is a weekend for us here.
I already help you configured your Joomla user group "Registered" to have permission to comment on your discussion page, you can refer on my attached screenshot below which setting i enabled (under ACL section).
I have created a test user on your site and it showing for me as you can see here http://take.ms/udKl6y. Maybe you can explain more on how you wanted to achieve this. Please advice.
May i know which user your are viewing them with? Is it non-logged users? Or maybe you can provide us with those access credentials for us further check on this issues.
Also in backend I cannot define a default theme, and does this matter?
May i know which components are you referring to? Maybe you can provide us with more explanation in order for us to have better understanding.
On my end it is showing correctly as you can see here http://take.ms/ymfne. Maybe your browser got cache.
Sorry I understand what you mean about Publisher ACL
I have checked this by creating a new user under publisher group, as it is working fine on my end as you can see here http://take.ms/NPPNy. Maybe there are issues with your browser or maybe it got cache or browser compatibility. May i know which browser are you using. Maybe you can provide us with full screenshot on these issues.
Oh, sorry for confusion caused above. By the way, you are most welcome. Glad to hear that your issue has been resolved now.
As a gentle reminder, kindly start a new thread if you have any other issue in the future so it will be easier for us to manage your inquiry. I will lock and mark this thread as resolved.