Foamy quickbread batter that didn't rise enough...

As far as the bread not rising enough, it could be that the recipe wasn't written perfectly and they should have called for more baking soda and/or powder. It could also be that yours was a bit too old (more than 6 months) and lost some of it's power (though one of them at least we know was active, by the foam :) :) Sometimes we also measure things like flour differently than the recipe author does, so we can get different results; it might be worth reading the front pages of the cookbook to see how they measure flour (or searching the blog, or asking the blogger). That can affect the bread's rise and make it not rise enough. If you used yogurt when it wasn't called for, perhaps that affected it, but if the recipe called for yogurt, then the recipe author should have figured out the proper rise. Hope this helps! Oh, and the King Arthur Flour baking hotline is a great (free!) resource to problem solve stuff like this - I love them!!!

Often when a batter includes both soda and powder, the soda is there to both promote browning and neutralize some of the excess acid so that the baking powder can do its work. The relatively small amount of acidic liquid isn't enough to cause lift when it reacts with the soda, so the powder is there to finish the job. Baking powder is nearly always double acting so it contains all of the acid it needs to leaven. Too much of either can cause bitter and/or soapy flavors. So that's why there is both. The foaming is the baking soda doing its job, so bake the cake quickly after mixing to take advantage of the initial reaction...the baking powder will do its job in the oven.

The batter is foamy because the baking soda is reacting with acids in the yogurt, creating pockets of carbon dioxide which expand in the heat of the oven, causing your bread to rise. You'll also see some foaminess resulting from the baking powder, which contains baking soda and two acids, one of which reacts with water (in your yogurt, for example), and the other with heat, to also create carbon dioxide. The moral of the story is that your foaminess is entirely appropriate.

As to why it didn't rise enough, how much did it rise, and what were you expecting? If you can tell us that, we can give you a better answer.