Customize wordpre theme

I have a wordpress website and need some easy customizations,the site is [login to view URL] it uses this theme [login to view URL] All I need is 1) make registration process clear,after registration user must recieve his username and password on email,nothing more 2)add top 10 plugin like in the demo 3) share on tumblr button under the post(like ther are share on facebook and on twitter buttons) 4)add facebook and tumblr page buttons as in the demo THAT'S IT,nothing more,I think this is a pretty easy task but I personally have zero experiencein building the sites. The theme itself is not bought,it is a template