So I've been experimenting a little more with houses (wood vs. stone) and there does seem to be a slight reduction in the use of firewood with stone houses compared to wood houses. When I started keeping track I had mostly wood houses and the firewood usage was around 2700 per year. When I upgraded most of my houses to stone, the fuel usage dropped to 1960 per year.

So is it worth upgrading your houses? Still uncertain, given how easy it is to produce firewood it doesn't seem like a huge difference, but maybe there are some more benefits that are less easy to measure. Like maybe your workers don't need to go home as often to warm up in the winter or something.

There was a post on the official forum recently on this topic. Nothing definitive, far as I can tell, however.
http://shiningrocksoftware.com/forum/discussion/1696/the-official-stone-house-worth-it-post#Item_6

I can't wait until we can get access the mod-kit - hoping we'll be able to view files and actually get more of this type of info. :)

I can't get livestock. Any ideas?

Any time the livestock trader comes through, he's unwilling to take any of the goods I have; everything has a value of zero for him.

Every trader that comes through is looking for different items to trade for. If you are wanting livestock you'll need to keep items other than food in your trading post. A food trader will trade for food but not a livestock trader.