Use of .mobi domain ext with Mobile Joomla

Making my site mobile friendly is a must, and I am thinking of trying Joomla. Should I use a mobile template or can I use any template and add the MobileJoomla app? Maybe both is recommended, and what about using mobile CSS.

What is working for you? and how is it set up? Links welcomed, please tell which template you are using or if it is custom.
Thanks is advance.

MobileJoomla includes 4 templates (mobile_iphone, mobile_pda, mobile_imode, and mobile_wap) corresponding to different markup languages used in mobile deveices (html5, xhtml-mp, chtml, and wml). But you can use any other mobile templates or make your own unique one.