Change WP website theme & slight design changes

I am looking to change my theme to:

http://themeforest.net/item/gym-extream-gym-and-fitness-wordpress-theme/3581558

But I would like it looking like this:

http://ashleyhorner.co/


I love it how she has the massive photo of her on the side, could you:

Is it possible to change the theme over like hers, so I have a large photo like that also the video slides are wicked??

-Also will all my blogs change over with it or would I have to add them on separately.

- Will I lose my rankings on google as I am no.1 UK's fitness model

My website is http://www.kellyrennie.com

Thanks

Kelly