I don't profess to having any experience using this, but hopefully this will help you to work it out a bit more.
I've put the house in and rotated it to a jaunty angle. If I have World Transform selected and use the red gizmo arrow from side to side the house will scoot across the ground and remain half-buried.
WT-1.jpg
Selecting Local Transform changes the gizmo orientation so that it becomes based upon the orientation of the asset - can't think how else to describe it. Now when I grab the same red gizmo arrow and move it from side to side the house moves as if it's on a slope...
LT-1.jpg
LT-2.jpg
Possibly also worth mentioning is the Snap Rotation section. This relates to when you rotate an asset whilst pressing Ctrl. By default each increment will rotate the asset by 18degrees, so to turn it by 90degrees it'll take five steps. Change the number in the box to be 45 and it'll take two steps to turn the asset; 90 and it'll be one step. And so on... The little radio button is supposed to select whether it uses the default 18degrees or the figure that's been entered in the box, but at the moment (until it's been fixed) the figure in the box will always be used.
Hope that makes a bit of sense and is of some use. You're now at the same level of understanding as me.
