Can't really do that within the same modifier. Better to use separate objects. Anyhow, those objects are separate in real life, so your model should do the same. This is worth a read (help file) http://help.autodesk.com/view/3DSMAX/2016/ENU/?guid=GUID-9F0E9AC3-FAE6-46A6-83F3-591084220B12 I used all three methods recently…
That's a definate improvement, it looks more realistic from a texturing standpoint, also theres some nice details in the back. And as for your question, I wouldn't use tileables on props, just buildings like this. Tileables should work for pretty much all architecture you are doing, but it requires more texture memory to…