Ad.1 It doesn`t make any problems. More about eZ pub and UTF8 here. http://ez.no/ez_publish/documentation/configuration/configuration/language_and_charset/unicode_with_ez_publish
Ad.2 This can be done by add some changes in CSS files (site.css).
Ad.3 To change the default language of the interface, you have to just change the setting in site.ini. .ts file cowers translation for the wizard. To translate all parts of eZ publish, you also have to translate the default database content, such as class names, for example. This means that you have to distribute a modified database together with the .ts file.