All 3 main content placeholders and divCenter divLeft and divRight must be there or it will fail to load your master page and instead load a failsafe master page. Check your log for errors it will tell you when it fails to load the master page. You can position them any way you like so divCenter can be first but the others must also be present.

It should have all the same required things as a normal skin like <portal:StyleSheetCombiner, <portal:ScriptLoader and the divs and content palceholders mentioned above.

You've purchased Mobile Kit Pro, so you can study that skin for ideas. Lots of important things to configure feature layout and options can be learned in theme.skin of Mobile Kit Pro.

Hope that helps,

Joe