Doodads moving around would be by triggers to remove them, then re-add them where you want. Arabidnun has given you a tree regrow trigger not too long ago, use that and learn how to remove and readd.
Secondly, well basicly, without triggers..no you cant. But all you need to do is go into the object editor, create a new building, and go down to "Art - Model File" (I think thats it) anyways, and change that to what doodad you want. Then just give the builder that building.