Two questions :
1. I currently run Twenty Ten on all my websites with no changes to any .php. I do have custom headers. I am thinking about changing some of them to Twenty Eleven. Should I assume that this is very straight forward and a matter of just downloading the new theme in the admin appearance area?
2. I have a new website that I am setting up and would like to use the portfolio style theme, I think it is called 'Slider'. It is black background with image slider on the main page. Does anyone know if this theme is user friendly, fast loading, versatile etc?