I have dos questions...

[Mios Dio]

I don't think any of these questions break the golden rule. I don't think they were answered in the wiki either, but if they are, sorry. Ok, first question:

Can skills be improved? I think I heard they can be, but I wasn't quite clear on how.

And say I wanted to build a shack at some point. Can I add on more rooms to a shack? Even just small shack rooms?

[Sho]

Skills improve as you use them, though some improve faster than others.

Not certain, but I think that if you can build a building outdoors, you can build it inside another building. So you can put a shack inside a shack, a building or room inside a shack, or anything else on the Buildings list that's not an extension.

[Talapus]

Skills can be improved. They do increase whenever you attack something, or whenever any work is done on a project. You can add other rooms to any building. In fact, any building can be built onto an building (such as a stone building onto a shack), with the exception of extensions which can only be built on buildings of the same material type (stone extensions can be built onto stone rooms and halls, and wooden extensions can be built onto cottages, and possibly shacks, although I am not certain of that).