Hi there,
Google Plus and Instagram are not part of Connect at this time, so it’s not possible to add them. I will pass along your suggestion to the team that works on Connect, however. If those services are added in the future, we’ll let you know!
In the meantime, you can add links to your Instagram and Google Plus accounts inside widgets in your sidebar (I see you have done something similar with a footer widget already). We also have an Instagram widget that will allow you display your Instagram photos in the sidebar.
Cheers,
Michelle