Need help in customizing homepage links

I need help in using Blogs MU theme. I have listed the problems I am facing.
1) How to change the login link given at top right.
2) How to correctly point to the (correct) dashboard of the (currently logged in) user at home page header. (refer pic)
I need to point that link to persons profile or dashboard of that particular sub site. Not to the dashboard of multisite.
3) How to change the picture in the header. (refer picture)