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I dont see any problems with you making/modeling your site after that one, aslong as it uses a diferent desing (of course). lol
as for versions of xoops.
2.0.16 is the "offical" version
but 2.2.4/2.2.5 is still around, heck ive recently use it in a site.
not all the moduls work in 2.2.X versions, so caution should be held.