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For myself I much prefer "none" for the start page. I either put blocks in there or more often I create a custom block or whatever it is I need there. There is nothing magical or different between any of the positions, it is only a db value. How it looks is up to your theme and CSS.
So yes, you should be able to put any content on the start page within the limits of XOOPS and your own creativity. BTW, my first page content is center-center, no problems. Check your theme and of course the content you are trying to present there.