Can I freeze this type of cake (http://smittenkitchen.com/blog/2008/04/lemon-yogurt-anything-cake/) and what is the best way to defrost it?

Double-wrap it in good-quality plastic wrap to freeze, then that at room temperature. Even thawing overnight is fine. Hint from a lesson learned the hard way: if you have animals, perhaps hide it in the oven to thaw. Hang a kitchen towel on the oven handle to remind yourself that there's something inside. That from another lesson learned the hard way.

Yes, you can. Cool it thoroughly before wrapping in plastic. Defrost with the plastic still on (as the condensation will cling to the wrap, not the cake). I'd just leave it out on the counter for a three or four hours, but you could defrost in the fridge for a day or so, if you prefer. Give yourself enough time to let the top of the cake dry off a bit, after defrosting and unwrapping the plastic, before sifting icing sugar over it. (Do that immediately before serving, so that it stays pretty.) ;o)