Welcome to Meta Jamie! 
I’ve had a look through some plugin and theme-component available here on Meta and found some that may be of interest to you.
As for an expandable user section, I found User Portfolio. That seems to be the closest thing that allows users too add pictures to their profile. However, a caveat is that this is publicly available for other users to click on. So may not be the best solution if users want to do something in private.
As for social media, users can add their social media sites on their profile so that they can share their work etc.
To achieve a blog post style topic there is this TC.
Finally, as for a who’s online there is a plugin available for that
Hope this helps