Just to build on @SynysterMuskrat, it does sound like there will plenty of arhictectural customisation for us to play around with, columns, balconies, multiple floors, different roofs etc. As well as this I would imagine the material you use will depend upon the style and properties of the structure - an example that was given during the kickstarter is that ‘perhaps Ironwood makes for stronger defensive walls than Oak’.
As for things like large windows/ doors … we haven’t heard anything yet, but who knows! I would imagine if we have normal doors/windows, that larger ones will find their way in somewhere.
As for specific defences we haven’t heard much. Regarding moats I would hazard a guess and say yes - I mean you can alter the terrain, so a natural step would be to manipulate water to create a moat.
Regarding actual architectural style’s, we haven’t