@khall,

But I cannot get rid of the 'Be the first to comment' box or if someone has commented, it says 'Join the discussion' - I saw someone else had this issue and I went to the Settings page and followed the instructions, but despite clearing my cache etc, it's still there

Don't follow you well. Please try to explian using a screenshot. 

I see that the stick comment and lock comment are seen by admins only! 

yes, those buttons are only visible for high-level users like admins, moderators, etc. 

More info here: https://wpdiscuz.com/docs/wpdiscuz-7/plugin-settings/comment-moderation/#stick-button-%E2%80%93-stick-a-comment-thread

I want to hide the suggestions heading as none of the suggestions that come in will be published publicly. 

Could you please clarify a bit? 

@khall,

There is no way to hide the main comment form. I may suggest you remove the textarea you've created and just change the phrase 'Be the first to comment'.

@khall,

Comments are publishing straight away but they should be held in moderation. I believe i have specified this wherever it needed to be specified. Am I missing something?

Comment moderation doesn't have any relation to the wpDiscuz plugin. It's being handled by WordPress. I've found the following article, it should be helpful for you: 

https://www.wpexplorer.com/wordpress-comment-moderation/

Can I hide the '1 Suggestion' line completely (shown in screengrab).

You can use the CSS code below: 

#wpdcom .wpd-thread-head .wpd-thread-info {
   display: none;
}

Put the code in the Top Admin Bar > Customize > Additional CSS > "Additional CSS" textarea, save it, delete all caches and check again.

Please don't forget to press Ctrl+F5 (twice) on the frontend before checking.

@khall,

as I've already mentioned comment moderation doesn't have any relation to the wpDiscuz plugin. It's being handled by WordPress. You should check the points mentioned in the article I've provided and found a solution.