Ok, this is driving me nuts! How do I rotate a building? I have read to "press R", "scroll on the mouse" etc but none of them work. Thanks in advance!

I haven't done this, and I don't know if it works ( i just bought crusader yesterday, first stronghold game)

But maybe try rotating the map with the compass ( hold right click, drag to compass ) and then place the building?

I don't think that you can rotate buildings, because they are no 3D models. They are sprites. But this is not really necessary. Only for the castle gates it's necessary and there you choose right from the menu if the gate should point down left or down right.

You don't need to rotate the buildings. They can be accessed from all angles. IF you place a building near the wall, it's roof will be "attached" to the wall. But it's only cosmetic difference afaik.

Yeah you can't, it's weird though because if you rotate the map and place the building, it will be facing the way you want - but when you rotate the map back the building resorts back to facing the original way.