Network Theme customization

I am trying to do the following things in the Network theme I purchased. Please show me how.

1. I have a multisite blog. The icons that display on the middle of the page are the recent blogs from across my network. But the image of each blog keeps on using the super admin’s image, instead of customize for each blog. Please tell me how to change this.

2. Also there is a search bar underneath the name. I would like to disable that since I already use the Global Search as a widget.

3. Lastly, I do not want the Network theme to be use by other bloggers. Just by the multisite admin. Is there a way to disable that so they cannot see or activate it.

Thank you.