I’ll try and answer some of the above…
Plugins
See post #5. I agree with Mr Papa’s list. But… that is as far as our own forum goes. If, for example, you will not be allowing your users to upload images/files to your server then it would be pointless installing the file uploader plugin. You really do need to decide for yourself what you need.
Themes
The theme we use here is called ‘Reboot’ and is one of our premium and fully responsive (mobile) themes. We use the ‘Orange’ overlay bit there are several others. Icons are supplied but – as stated above – you are free to change all of any of them as you prefer.
User Approval
You mentioned wanting to approve new users. Users are NOT the province of Simple:Press – they are controlled by your WordPress site for which Simple:Press is merely a plugin. You will need to investigate membership or sign-up plugins to achieve this.
Installing Plugins
It would be most unusual for us to install plugins for you. And it really is straightforward and easy. If you really feel you require help please send a PM to the forum admins here (all 3 of us) with a detailed list of what you need and we can prepare a quote for the work.
Post Moderation FAQ
For users new to Simple:Press there is a complete ‘Getting Started’ section in our codex (see menu in the sidebar) which covers the basics including a section on permissions and user access control. We recommend spending a few minutes looking through these pages to better understand the forum relationships and stricture.