Mixing almond powder in the cake mix makes it more elastic and easier to roll. Roll the cake when it is still lukewarm to avoid breakage.
Translating from the metric system to the US measures can make it less precise. For accuracy and better result with this recipe, I would recommend using the Oz. measurement with a food scale.
Find Yule log décor items on this website: http://www.scrapcooking.fr/en/. Order online, delivery in the US is available but expensive. I would suggest you find a French bakery in your area and see if you can buy some of the décor from them.