The SiteLogo control in the layout.master file of your skin should automatically make a link to your site root. If all else fails you can just put an image there and link it yourself. 

To solve the tabs you need to view the source of the rendered page and see what is different, where is it getting the yui javascript and css from.

Unless you have different settings in Web.config it should get the script and css from the google CDN.

If you are using a custom skin it may be something not the same in the skin. If you made a custom skin for an older version then you should see the notes here:

http://www.mojoportal.com/important-skin-changes.aspx

Hope it helps,

Joe