How tall can I make the houses?
There’s no limit, provided you have the “Main” as the lowest part and “Top” as the highest part. We recommend you do not go any higher than 4 storeys as it would start looking a little strange. Physically, these kinds of wood based structures would not go above 5+ storeys as the wood frame would collapse under the weight.
Why are the trees are NOT set up for windzone?
Please see foliage section
If you really want windzone, you can switch the material shader over to Nature/Soft Occlusion. Then assign the individual LOD mesh you want when adding trees to your terrain tool. This will allow you to have a bend factor, and windzone will then be enabled.