casuarina: how to keep it as it is

Hi all,
(I'm a real bonsai novice)

Is it possible to keep a Casuarina seedlings just the way it is now? (I don't mind if the trunk remains thin for ever.)
What will happen if I continually pinch its top part for the rest of its lifespan? Also, is it bad if I cut off most of the shoots that strike, so I can keep the general pyramid shape and the height of the tree?

This picture I found on the internet is quite similar to the size and look I want my own Casuarina to have.
http://www.ipmimages.org/images/768x512/5285005.jpg

Thanks for any responses.