As for the plugins you’ve mentioned I’ll try and give a quick run down on each one.
SEO Optimisation – The only plugin we offer for SP is the Google XML Sitemap plugin which isn’t a ‘stand alone’ plugin and instead it integrates with any of the WP plugins listed on the plugin page. The rest of SP’s SEO options can be found in the admin panel under Forum > Components > SEO.
Social Media – We have a nice selection of plugins that could work here for you, Share This, BuddyPress Integration, Thank Posts is probably the closest thing to ‘Like’ although we also offer Answers Topic and Reputation which should probably be considered for giving your community more interaction with each other.
Displaying adverts within the forum is a straightforward process. See How to display ads in the forum, and of course Creating a child theme.
Not sure what you mean by ‘roottheme’.. Unified and Reboot are both desktop and mobile themes all in one. We use Reboot here so you can see how it looks on desktop and viewing this forum on a mobile will give you a good idea of how it looks in responsive mode too.
I’d like to say that if you don’t know much about HTML / CSS then customising Simple:Press is relatively easy but only if you are willing to read documentation. If you are just installing forum plugins, a theme and setting up options then you shouldn’t have any trouble.
Unfortunately we don’t have any video tutorials but there is plenty of information in our codex in the sidebar on the right hand side here. It’s always worth searching the forum here to see if you can find what you’re looking for and of course open up a topic if you need any help we are always here.
As for Genesis, I’ve never used it personally. Mr Papa set up our WP theme here and from memory has nothing but praise for Genesis. It’s definitely something I’ve been meaning to try out but as far as I can see it requires quite a lot of user input / customisation which is great for some, not so great for others!..
Hope that helps.